It is a bit boring IMO, in terms of gameplay it's almost all the same (Just started "Finding Alice" or something with Alice in the title).
Still, it's quite fun, AI is great, not too buggy (though I have had some issues where the game freezes for like 30 seconds then resumes without issue).
There are a few niggles, rocket launcher doesn't take chunks out of the walls, though shotguns/AR etc do, and some spoken dialogue doesn't match up with its subtitle text.
I run 1280x960, most stuff on high, 4xAF, no AA w/AMD64 @ 2600MHz and a 7800GT.
Can be a little choppy sometimes But it's totally playable.
Some of the puzzles are very Half Life-esque (which is both good and bad), some bits are a little silly, and it can be easy to miss little bits that you need to do to get to the next area (eg: like the OP's problem, which I also had).
Also, I feel like I'm lost pretty much all the time, but I'm usually managing to go the right way, because it's fairly linear, it blocks off any way that's the wrong way, and usually there are a couple of ways to get from A to B, so while I feel lost, I'm not usually really lost unless I've missed some obscure switch or doorway.