tomimt: Still Life 2 is heavily inspired by Saw movies and the like. Basically it's an idiotic murder mystery that takes place in a single location where the killer plays cat and mouse with the victims.
For me it was a huge disappointment, as it barely touches the plot of the first movie. The killer is revealed in a quick subplot that fits very poorly in the rest of the game.
I would say that it's more a shortcoming of Still Life 1 than Still Life 2. If Still Life 1 had been chapter or two longer no one would be complaining. Only unanswered questions were who was the killer and what happened in Los Angeles and the game established that Gus didn't participate to events of Los Angeles. It's not enough material for a full length adventure game. Still it's something they couldn't really leave out, because then people would have complained that Still Life 2 didn't give any answers which people wanted.
And like I said earlier, I did find it refreshing that they told new kind of story in Still Life 2. Only common things which the 3 games of the series share are McPhersons and serial killers. Post Mortem was an occult murder mystery with stuff like Baphomet. Still Life 1 removed supernatural elements almost completely and told more mundane story about serial killers. And Still Life 2 is about being in a house of horrors with a serial killer. Naturally some people wish that all 3 games would be more similar with each other, but other appreciate the diversity.