I've been using LogTen Pro for 4 months and think it's a great app. I have not experienced data loss or corruption. Note that the first 40 hours of log entry is free so you can try it out... Be aware that if you enter a flight time, then enter a flight start and end times for the flight it will replace the flight time with one calculated from the actual times entered, makes since, but you need to enter either one method or the other.

I like the customization options for the reports. As a student pilot I have been able to create a custom form that address all the areas needed for the PTS.

Fly safe.