CharlesGrey: I remember playing one of the sequels on Gamecube -- was it Blood Omen 2? -- and found it rather disappointing.
Azilut: Blood Omen 2 is the black sheep of the franchise - it was made by an entirely different team and mangled things so badly that some fans (myself included) consider it non-canon. The other sequels are worth playing, though - don't judge them by the behaviour of their drunken idiot cousin Blood Omen 2.
To be honest I'm not the biggest fan of any of its sequels -- they all seem to suffer from Laracroftitis. ( I said "titis". Hurr. ) Back then the Tomb Raider games were immensely popular and commercially successful and as a result all of the major studios, especially Eidos, tried to apply the Tomb Raider formula to any new action game they released. At some point I just grew really tired of the box-pushing and silly switch puzzles. It's especially awkward when your character is supposed to be some ancient superhuman bad-ass. And yet there you go, pushing around boxes.
As for Blood Omen 2, in particular ( I think that's the one I played ), gods, there was so much wrong with that one. Aside from the aforementioned annoying gameplay elements, it lacked so many things which made the original game fun. Most of special abilities were either gone or severely limited. I think there were almost no weapons, armour or usable items, either, so you were stuck using the same repetitive combat mechanics throughout the game. Didn't help that I was playing a localized German version, which also had terrible voice-acting.
Oh yeah, and the AI was just embarrassingly stupid. I remember there were situations where you could jump on a table, and any enemies in the area would no longer be able to attack you. A. Fucking. Table. :|
Now compare that to games like Resident Evil 4, where enemies would break down even locked and barricaded doors, or use ladders to enter through windows. Playing that village sequence in RE4 for the first time pretty much makes you wet your pants -- compared to that, the enemies in BO2 were just sad.
Other than that, I've only played Soul Reaver, back on the PS1. Never finished it, but it was pretty decent at the time. In fact, I considered grabbing a copy during the Insomnia sale, but I ( just barely ) missed it. I'll probably buy a few games of the series on here, at some point. First and foremost I'd still like to see the original Kain on here, though.