The IC-2100 is Icom's newest single-band 2m mobile transceiver. For the specs and a pretty picture, check out this link to Icom's page. I hope, however to take you somewhat beyond the specs with a review of usability, and the problems I've had.
After I picked up my radio from HRO in Portland, I took it home, and immediately put it on a power supply to try it out, and press all the buttons. My first impression was a good one, with a very clear, easy to read display, good layout of buttons on the face of the radio, and delightfully button-filled microphone. The mic felt kind of cheezy and plastic compared to many hand mics I've held before, but that wasn't too surprising.
The physical makeup of the rig is good. The case is in two pieces as far as I can tell (haven't taken the cover off yet): the top is composed of a weighty heat-sink, and then there's a flat panel cover on the bottom with four machine screws in it -- I assume that's the service access. There is no fan on this radio, but Icom claims (from their web-site): "Usable Temperature Range: -10°C to +60°C; +14°F to +140°F". So, I assume it will survive quite nicely unless you live in a very hot area and transmit at high-power a lot.
The front-panel buttons (as you can see if you take a look at the picture Icom has on their web-site) are laid out differently from the IC-2000. In this new model, they're all directly under the LCD, and the labels are now *inside* the LCD, which allows you to read them when it's dark in your car or truck. The downside of this -- they're tiny labels! This radio may have large digits, but you'd better know which button does what by feel before you can do anything with them while driving. I have to get within a few inches to read them, and my mounting location is down near the base of the gearshift.
A note about the mic -- it has a plastic cover which snaps over the lower half of the unit, in order to cover up the DTMF keypad. It leaves the upper buttons (up, down, VFO, MR, "B" [more on that later], F-1 and F-2) exposed. I've discovered that this is actually my preferred operating position, since I rarely have any reason to adjust the radio much more than frequency or volume. However, that cover is not attached in any way, and would quickly get lost or broken if you take it off very much. But, on the plus side, you can operate almost all the functions of the radio from the mic, which is a real benefit since you can bring it right up to your face if you need to read the little labels.
A brief note on the "B" button. When I first got the radio, I was somewhat puzzled by it, since the manual just said "no function". I imagined it was probably for a function not enabled in this radio -- I was right as it turns out. This is the same microphone Icom uses for some dual-band mobiles, and that's the "band" button. There's something kind of neat about having a useless button that goes "beep" when you press it, though.
The first impression was marred when I noticed that the controls on the microphone (including PTT) didn't do anything. I took the radio back, and got a different one, which appeared to work better. I'll talk a bit more about this later.
While I had the radio inside, and on the power supply, I took the time to program the memories I would be using -- weather channels and the local repeaters. There is (as one would hope) a way to skip over certain memories when you're scanning. Setting memories was fairly straightforward, and after reading the manual on this point once, and referring back to it once, I was able to set memories with no trouble. The stored memory does contain everything you'd hope, including frequency, offset, + or - duplex for repeater, CTCSS tone, etc.
One interesting "bell" on this radio is the ability to change the backlighting color and intensity. The color can change from amber to green, and the intensity can be adjusted to any of four positions (from "bright" to "almost off"). I've found that level 2 (1-4 are available) works as an all-around level of brightness.
Once I finally got the radio into my car (it took a bit of engineering to fit it into the center console of my old Toyota), and snaked the positive power lead out to the battery, I was set. I turned it on, and basically started operating. One thing I did which may be a new practice (I've never installed a mobile radio before, so I'm not sure) was to make the ground lead of the power connector as short as possible, and just run it to the first available chassis ground. According to Ray, KI7TN, at HRO, this reduces the amount of alternator noise drastically. As far as I can tell, it works fine. I've had no reports of alternator whine or popping. In my installation, "very short" means about 10 inches long, or about 3 inches past the inline fuse (there are fuses in both leads).
The controls, if you can remember what they do, are easy to locate without looking, and the large frequency/memory knob is quite good. It has detents so you can tell when you've moved one memory location or frequency step without staring at the display. The volume and squelch knobs are tiny, but easy enough to use. I would have preferred if they were a bit larger in diameter, for finer control, but their current setup seems adequate.
Using the microphone to control the radio seems pretty straightforward, as the most commonly used buttons (up, down, VFO, and MR) are quickly identifiable by feel. If you plan on using the DTMF or keypad controls very much, definitely take that little cover off, and leave it in the box. Although it'll keep you from bumping buttons accidentally, the chance of losing or breaking it is pretty great.
Receive audio is loud and clear, but some installations will suffer from the downward-firing speaker. The reports I've gotten about transmitted audio have been pretty good overall. The radio will put out 5, 10, or 55 watts of power, and I've been leaving it in the lowest setting for the most part (I do most of my driving in downtown Seattle, in easy 5W range of the repeaters I use).
Speaking of downtown, there's the intermod claim that Icom makes about these radios (IC-2000 and IC-2100). I don't have a lot of experience to draw upon, but this rig seems to do pretty well. I had previously been using my Yaesu FT-50 (with about 5 cables snaking from it) as a mobile, and it was paralyzed by intermod in about half the places I drive. This radio occasionally chirps the squelch in the worst parts of town, but seems otherwise unaffected. I wouldn't say it's the perfect radio against intermod from paging transmitters, but it's pretty darn good.
Since I bought this radio for mobile operations, there are a few things I haven't yet encountered. Notably, I haven't tried using this rig for packet. There is no mention of packet radio anywhere in the manual, and it looks to me (looking at the illustration of the RJ-45 mic connector in the manual) as though you'd have to construct a spider-web of a cable in order to get 1200 baud packet to work. Since there's no mention of packet, I assume the radio is entirely unsuited to 9600 baud, and I would recommend you find a more suitable radio for packet operations.
Finally, I wanted to mention this voltage problem I've been having. I first noticed it in the second radio I brought back from the store. When I plugged it into one power supply (neither of these are really "good" supplies for amateur radio, as I wasn't at home), it would work fine but not transmit (not enough power in the supply, only 2A or so). When I plugged it into another supply, with a bit more power, it wouldn't respond to the microphone controls at all! I eventually figured out that it was a voltage problem, and determined rather unscientifically that the cutoff voltage seemed to be 12.6 VDC. Above that point, it all worked fine. Below that point, the microphone stopped functioning, rendering it a "receiver only" radio. It also occasionally stuck in transmit mode if the voltage was too low.
I went back and tested the voltage again, after talking with Icom's tech support. I got some strange results: the cutoff voltage started at 12.38 VDC, and slowly crept up to 12.69 VDC as i repeated the test. I'll be bringing the radio in for tech support to look at on Monday (they claimed they've never seen one of these radios with this problem). I've received one other report of this problem from a list member, and the first radio I had suffered from it rather severely (since 12.7 volts wasn't enough for it).
Icom tech support says that the radio should be functional within +/- 15% of 13.8 VDC, which is about 11.75 to 15.85 volts. I'll be very interested to see what they have to say after they take a look at the radio.
Update: I've gotten the radio back from Icom, and they added a "factory update", which means, I believe, that they updated the control code for the CPU. If you have an early-serial number 2100, I strongly recommend that you send your radio to Icom for this modification, as the low voltage cutoff could prevent your radio from working in an emergency situation, such as when the engine of your car won't run, or when you are running low on battery power in any non-commercial-grid situation.
So, overall, I'd say the 2100 makes a fine mobile radio. If you want to have it available as an emergency radio for situations when you can't run the engine, check it with a variable-voltage supply or a fading battery before you count on it. I'm definitely happy with it, and will be happier if Icom can come up with a fix for the undervoltage problem. At a price of $250 (which includes a $20 discount taken at the register), it seems like a nice, solidly built radio.