NOT VERY RELIABLE Rated 2 out of 5 stars
Problems I have encountered repeatedly include:
1. tabs from recovered windows are merged into one window (loses different windows) (merge windows option is turned off)
2. sometimes after crash recovery file will not load...causes FF 3.5.5 to keep crashing. Only way to recover is to restart the computer.
3. Sometimes recovery file after crash is corrupted and cannot recover tabs and windows.
Using FF3.5.3 on Mac OS X 10.4.11