I bought this after recently finding an original Mac copy in my parent's loft and remembering how long it took me any my dad to figure out the puzzles in the days before walkthroughs!
When playing through this time I'll admit that I found myself stuck on more than one occasion and going online to find the solution. If you do this it will cut the play time down to around about 4 hours but if you choose to slog it out on your own you should add at least a couple of hours to that.
Although relatively short by today's standards I thoroughly enjoyed going back to this classic which I can also say has aged very well. I never once got the impression that I was playing a game dating back to 1995, especially with the cut scenes. What this game lacks in longevity it makes up for with an engrossing storyline, fun characters and good, challenging puzzles. Basically, everything that modern games tend to lack! At this price it's a must and you won't be disappointed, particularly if you have played the game before when it first came out (I could barley remember anything about the puzzles).
A few technical things I wondered about before purchasing... Yes this game does run on Vista (straight off the disc) without any problems. Also, you have to push F1 to get the save, load etc. menu up - the pdf manual on the disk doesn't make this clear but there is a word document explaining it (yet another puzzle to be solved).
All in all, very pleased and if you like revisiting old games this should be in your collection! Not quite a 5 star because of the lack of longevity but still a well aged classic.