OK, finished it (not out of the dungeon, but Ilyich & Co. are dead). Protagonist is a halfling thief - at this stage of the game, utterly useless except for the two traps per day; picked up Immy, Minsc and Jaheira but did not go up to Yoshimo's floor yet.
The Shadow Thieves are definitely nicer than the Rune Assassins. With the Rune Assassins, everything had to go perfectly in order to win in an unbuffed fight (that is, it's easy if the Runi is attacking a Stoneskinned Sorcerer, but if you were to simply attack him unprotected, he'd massacre your entire party). With the Shadow Thieves, it's the other way around - in order for a character (mostly Jaheira) to die, everything has to go wrong for the player. They did get me to reload a couple of times - while resting, two of them show up together with War Dogs and everyone was badly in need of healing so they kill someone. Another time, I got over-confident and he just stunned everyone (except Imoen who seems to be immune to all of their tricks) and killed me. I also appreciate the fact that they don't do more than around 30 damage on a backstab - it's annoying when a fully healthy character instanly dies from a 70+ lucky hit.
The Glabrezu works just fine - I lured him out first, and had Imoen kill him with offensive spells. He did chase her for a long time - all the way into Rielev's room.
[!--EDIT|Althernai|Oct 22 2002, 05:09 AM--]