It's too bad I was never able to play this around the time it came out. After I played it for the first time a few days ago, I'd have to say it's one of the top adventure games I've ever played--no exaggeration!
The good: Great characters and script, and a great plot which is nicely delivered piece by piece instead of one big exposition at the beginning or end. Interesting puzzles: although the usual "find X and use it on Y" kind of puzzle is still in the game, there are some more innovative ones as well. My favorite puzzles involved the secret codes in the game (but I like that kind of stuff already).
The bad: First, I experienced some audio de-sync, especially during a cutscene (but this may be a problem with my system rather than the download). But it wasn't a huge deal. Second is pixel hunting for certain items was very difficult. You really have to examine certain screens closely to make sure you get each item that you can and well...with certain items I think they were too hidden.
Finally, there's an issue at a certain point in the game that may stop you from progressing. You should check the support forums for this game if you find that you're unable to go any further in the game, because there's a solution posted for this (here on the GOG support forums).