I bought a pre-production one as a sample which has some bugs, but I think they have been resolved.
It is nice and small but takes a fairly good quality video, as good as any similarly priced dash camera.
Uses a micro SD card
Overlays GPS speed on to video
Breaks up files into short 1 min clips to avoid data loss when power is disconnected
Starts recording automatically
If you want something of even higher quality, then look into something like the Contour HD cameras. They're designed for recording sports like biking, skiing, etc.. but offer pretty good quality recording. No speed overlay, but they have a GPS model which records the GPS track including speed.
So far works great. Only problem so far is the videos don't playback in the software it comes with or with the websites updated version, which is also supposed to show your position on google maps while reviewing clips....still buggy I guess.
Still testing out different options to decide if ill keep this or return it for another brand.
Pic attached is in 1920x1080 resolution, can get wider FOV with 1280x720 resolution though. Screen cliped from wmp player while reviewing video.