This thing does not BITE Rated 5 out of 5 stars
Session Manager DOES WORK as advertised. I just opened 2 windows with 10 tabs each and caused Firefox to crash and Session Manager successfully restored all 10 tabs in both windows.
Since you are the only person (out of over 300,000 downloads) who claims that the crash recovery functionality isn't working, my guess is that instead of choosing to restore the crashed session, you restored an older session. Even if you did so, the crash session is still saved and you could have restored it.
If Session Manager didn't work, there would be a lot more people complaining here and in the support forum. Instead of calling for the extension to be removed, you should have posted in the support forum.
By the way, Firefox 2.0 has built in crash recovery for restoring tabs open on a crash. Session Manager just adds the ability to save and restore session and the ability to restore different sessions on a crash. If all you want is the ability to recover the last session on a crash, you don't need to install any extensions (Session Saver, Session Manager or otherwise).