Please forgive me if this topic has been addressed already, but assassins do not seem to be very formidable. It would be nice if they were able to actually kill an opponent when they successfully back-stab. Perhaps this could correlate to level (at first level, once per day, 2nd level, twice, etc.). Just a thought. As it stands, it seems like the assassin is merely a thief with a few less abilities.
With all this said, I think that this is a great game.

Hi Oldercloud, I’m sorry the assassin has disappointed you! The class was quite popular in the playtest campaigns.
In general, since the assassin fights as a fighter and gets the fighter damage bonus, he is more likely to hit and will deal more damage than a thief. If you are simply interested in being a stealthy damage-dealer, that makes him a better choice than the thief.
If you want more capability for instant kills, you might wish to have your assassin explore his options for using monster venom and herbal poisons. These rules are detailed in the Secrets chapter.

Thanks, Alex. The game is great.