It looks like a pretty small camera, the youtube demo footage looks pretty good, and it looks like they are going on e-bay for around 30 bucks after shipping. Of course with e-bay it's buyer beware, but the sellers are mostly Top-rated.
I don't know much about different models of cameras, but this looks like it would be pretty good undercover, and cheap!
the lil pen cams found in skymall magazine are pretty cool too. Not as cheap as the cool one listed above (hadn't seen that one before) but handy if interviewing in person.
You can find lots of moddable spycams for various applications with a quick search.
I don't know how you plan on using it but I've used one of the little security cams found at Sam's Club on paranormal shoots with great results in the dark. I didn't have to hide it or anything but it's small enough it could be hidden.
Here is the rub with these cheaper cameras. You've got to be very, very careful with them! If you are in the middle of recording and the camera runs out of power, you may be up a creek. Literally if you don't turn them off correctly or disconnect them from the computer according to procedure, you may have to reformat the camera! I've had mixed results with a Pen camera that we got for around $135.00 bucks. The button that you turn the camera on and off with broke once and I returned it for another, but what would have happened if I had video on it!! We also picked up a camera that looks like a Car Alarm Remote for around the same price. For $270.00 bucks I go in rolling with both cameras, that way if one fails you know you've got the other backing you up.
Once you work with them for awhile you'll figure out the cameras quarks. If you've ever got the budget, which none of us do anymore, check out this guy's site. Investigative Mechaincs, it's the place to buy full proof equipment. Mitch builds it all in house and backs his stuff up. He supplies everyone from Dateline to Foreign Intellegance Agencies.
Again, his prices are not on most of our playing fields, but if you've got a budget, he is the guy to go with! http://www.bagged.us/index-2.html
I have one of the cameras that CS linked to, It's an impressive little bit of kit.
On the supplied 2GB MicroSD card, it will record about 1h:20 ish, depending on what it's looking at.
The battery isn't flat after this, but I've not tested it with a bigger card yet.
It splits the files into 30 minute chunks of 700-odd MB each.
If you wanted to extend runtime with say an 8GB card (or swap cards and carry on recording), it will record with 5v fed into the USB socket. I have tested it with one of those "emergency phone charger" gadgets that use a DC-DC converter to pull 5V from an AA cell, as well as a phillips USB power pack.
It will shoot through a ~2mm hole in a thick shirt pocket with some vignetting, and sound is remarkably good for the tiny little mic that's in it - clearly audible in a meeting situation for example.
With a little TLC and perhaps a compressor in your NLE, it could be improved too.
I think the sensor is a CMOS, as it does suffer from shear, but for the price and size, IMHO you can't complain.