System Shock 2 is certainly not for everyone. It's a little rough around the edges, and the hardcore difficulty may turn off those who don't like a little difficulty. Anyone who can get through this will find a game that deserves its legendary status. An excellent story, tense atmosphere and gameplay that allows for true diversity, System Shock 2 is a treat.
Pillars 2 updates the engine and the mechanics of the previous game to a more enjoyable level, bringing forth a far better gameplay system. However, this comes at the price of the writing, which was not up to the level of the first game. Overall though, I think the gameplay improvements balance out, and the DLC especially raises the level of the game to an enjoyable state. Definitely worth a look, even if you're not a fan of real-time with pause combat, as they've added a turn-based mode.