My wife got me one for my birthday last month. The first one had the controller (hard plastic) broken and some of the wiring was messed up, so we sent it back. Obviously a previous return. The replacement came in and was in a box, looking much better.
I've used it a few times over the last 2 weeks, and it isn't bad for short hops (<30-45 minutes) in high 30 degree weather. I haven't used it more than that, though. I would agree with the others that responded, that for more than a couple of hours, it would be better to get something you could power off the bike.
The way it works is that when you first turn it on, it goes into "High" mode, and after 10 minutes or so, will automatically power down to low. From there, you can switch it to either Med or High again, but must press the switch that is in a chest pocket.
The heat is focused in between the shoulder blades, so no arm heating, or even other areas of your trunk. To knock the chill, that's fine, but definitely limited application. Wouldn't recommend if you live in Minnesota or Canada, etc. Advantage is that you wouldn't be tethered to the electrical system on your bike. And even without the battery warming, the vest is fairly warm and comfortable by itself.
If you were to get this battery operated vest, understand that it's got a special battery pack - NOT 2xAA - and I would highly recommend getting at least a second battery pack.
One last thing is their caveat that you aren't supposed to get it wet!
Just my $.02; no connection, yada yada.
--keeper of "The Beast"
2k Champagne LTC