Thats odd. I find backstab and poison are still VERY useful in ToB... Oh well. Most of the more minor enemies get rocked utterly with asssassinate ability... Oh, and you can get a pure thief to have 5 attacks per round. The only problem is the horrible THAC0...
Lol, for a fun illegal character, make a fighter, then dual to an assassin. Use Shadow Keeper to help. Its really quite cool, and is almost unstopable (was unstopable in SoA pretty much). With Use Any Item, you can have some fun.