Now having had one for a couple weeks, I can tell you a few things about it.
1) The heat sink is more than adequate. I've yakked for over an hour on 50W, and it gets warm, but not the least bit uncomfortable to touch. And it wasn't in an ideal location for air flow.
2) The user interface has some problems. Unlike the Alinco, the JT220M allows you to step into unused memories. The radio has 99 memories, and let's say you have 20 programmed. You press UP on #20, you expect to go back to #1. Nope, you go to the unprogrammed #21. VERY annoying.
3) Page 30 of the manual claims that the the microphone DTMF keys can be used to directly enter a memory number to jump to. This does not work. Although the radio is a fairly direct copy of the Alinco DR-235T, the Alinco does not support direct to memory entry, nor does it claim to. Manual misprint or design flaw, with 99 memories, the lack of the ability to jump to a specific memory is irritating. The "way to do it" is to press FUNC, turn the big knob to select memories starting with '0' (0..9), '1' (10..19), '2' (20..29), etc. Poor design.
4) Pressing the UP or DOWN key for 2 seconds is supposed to start scanning. If you hold it down for less than 2 seconds, it's skipped up or down a few memories. Hold it for more than 2 seconds, it goes into "fast up" or "fast down", allowing you to fast forward through memories. Hold it exactly 2 seconds, it'll start scanning. It's hard to get the timing exactly right. My Icoms, Kenwoods, and the Alinco just go into scan mode and stay there after 2 seconds.
5) The JT220M does not support AM mode. The Alinco does. I don't really care about that, some people may.
6) The PDF copy of the users manual is a scan of the paper copy. It's not searchable. I expect that to be remedied.
7) Although the microphone is identical to the Alinco EMS-57 in functionality, the plastic coating on the cable feels cheesey. The Alinco microphone, while adequate, can't hold a candle to the HM-133 the Icom radios come with (or at least some of them).
The PC software from Jetstream is seriously lacking. Yes, you can program a frequency, alpha tag, etc. You cannot reorder memories. If you want to rearrange them, you save the data file, open it in Vi (or Notepad or your favorite editor. Except emacs. Emacs sucks), rearrange the entries, renumber them, reload the file in the software, and reprogram. Feels like a Windows 3.1 software package.
9) Overall construction of the radio seems decent enough. There is a cut-out for the DB-9 in the heat sink. The radio does not offer the DB-9, which is present on the Alinco. Not important to me, but it does matter to IRLP/Echolink/packet users.
10) It's big. By todays standards, this radio is huge. The actual numbers aren't that much different when you compare it to a DR-235T, but it's thicker, wider and longer. As a result, it feels huge. It'll still fit in a DIN slot in the center console of a car (you'll need some spacers, it's not THAT wide, but it's just slightly less tall than a typical 1 DIN stereo).
11) The display is blindingly bright. Even on dim, I found it very bright in my car. The blue display isn't particularly helpful. It's not BAD, but I think the orange of the Alinco is a little more readable.
12) GigaParts had a killer deal on a DR-235T last week. I bought one. It's in my car, the JT220M is back in it's box. I'm deciding what to do with it. I don't really need it, and I probably won't run 220 in the house. But it's 50 watts. The Alinco is 25. I haven't driven my usual routes since I installed the Alinco to tell you in Atlanta if the 25 watts is going to make difference. Quite honestly, if I need more power, I think I'd rather just stick a Mirage 220 75W amp in the trunk and be done with it.
13) I have an info page on my wiki about the JT220M. http://www.tinymicros.com/wiki/Jetstream_JT220M
There's also one for the Alinco, just follow the 'Category' link at the bottom.
14) What sold me on the Jetstream was the 50W. Atlanta is in the foothills of the mountains, and I live along the ACF basin. It's not like Texas or Florida. Sometimes you need the extra bit of string. Is the 3db difference going to have an effect? I'll tell you in a couple weeks.