Many edits later:

I just picked up one of these and took it out for a long ride yesterday.

First, the manual needs to be read quite carefully. I had all sorts of problems figuring things out, but it's all in there if you read every word. Nits:I'd wish that the heart monitor's spot on the display could be used for something else if you aren't using the belt, rather than just showing "off".

Installation up was a bit of a bother. I have no lights (other than helmet), but I still couldn't get it to connect up for quite some time. Turns out you really need to put the sensor in the position shown in the pictures: right under the brake pads. Any further away and the signals don't reach (I tried new batteries, no difference).

On the plus side, it's a nice big display, w/ at least 4 things shown. I ended up setting the altimeter to be 0 at home and it tracked changes quite well. I mapped a route on veloroutes at 1750 ft of climbing: the altimeter gave me 1720 ft on the actual ride. It tracked going down an elevator quite well. The heart rate monitor worked fine.

In conclusion, I'd definitely buy it again. The above sounds a bit negative, but it does exactly what I want it to do: usual bike functions, heart rate, and altimeter, and all for $110. I don't know of any similar computers anywhere near that price point.