I've left it on the default settings, logging everything in NMEA format at 1 second intervals. It seems quite easy to change the logging interval and detail but at this stage, I'm hard pressed to imagine a situation where I'll need to as I've logged about 62 hours so far and only used about 50% of the 128mb capacity.
It's a little larger than I'd like because it takes three AAA batteries. I'm using eneloops and getting between 10 and 12 hours per charge (changing them as soon as I notice the battery warning light flashing, I don't know how long it would continue running if left to run flat completely.)
The logging seems quite accurate while driving and cycling, but has a lot of "jitter" while walking for some reason. It generally locks onto the signal quickly enough once I get outside, but again while walking it seems to take an unusually long time to lock on which is a little frustrating.
It's best feature is that it doesn't require any special software to access the logs. It simply mounts as a USB drive allowing the NMEA format log files to be copied off. This is great and makes it particularly attractive for Linux and Mac users.