I have 2 of them - one bought in 2009, new one just a month ago. I've been taking it everywhere, recording all my vacation routes, business trips, bike escapades, ... I have a few observations:
Pros:
- it works with Linux,
- it is easy to configure and change the parameters - originally it records position, speed, etc. every 5 seconds, this can be changed to max. 1 point a second; the configuration can be stored permanently,
- the detail level of information stored for each point can be selected - you can store only the time, or the 2D position, but also 3D position, distances, the visible satellites - there is whole list and you can pick and choose,
- the battery works for whole day after full charge,
- the memory is enough for a whole day of saving 3D position, speed, time and distances every second.
Cons:
- the battery charging algorithm in the old device made the battery swell, so the battery container does not close easily any more (the new device is too new),
- the switch on old device is unreliable - it does make a proper connection any more (but seemed flaky from the start), so the device sometimes turns itself off in the pocket or does not initialise properly and so does not start (the switch on the new one is better),
- the manufacturer ignored my inquiry about software update,
- the BT connection is not completely reliable for fetching the data - it breaks frequently with the new device, but works nicely with the old one. The broken connection means you have to start downloading from the start (and for full device is takes ~20 minutes),
- the new device seems to have short timeouts on serial-port-over-USB connection, so for 'high speed' of 115200 bps the connection with a slow netbook might break (you can use the slower speeds quite fine), the old one never had any problems,
- logging in ICE trains seems to be problematic - more often than not I had no data collected at all from the train, the new device seems to perform better,
- if you press the button to store a "POI"/way point, the normal point will not be stored - don't put it in tight pockets, you will have only way points, and no real geo-data,
- the instruction mixes LED colours/behaviour - the device behaves differently. This is not a big issue really.
On the whole - reliable, but has some minor issues. I would have given it 5 stars, if not for the flaky switch, swollen battery and no info on software updates.