This is a puzzle game, very simply. You walk from one puzzle to another, and solve all of them until you win the game. If you like hard-core puzzle games, this may well be for you. If you prefer your puzzles with more in the way of logical progression and purpose, or even a story-- an adventure game, say --this is simply not an adventure game. Anyone expecting an adventure is likely to come away sore disappointed.
By all means, do buy it for the puzzles and the oddly compelling atmosphere.
On a note completely unrelated to the gameplay, the original graphics (640x480) have not aged well, and while Masterpiece Edition is an arguably clever solution-- all the original models have been exported to meshes for your 3D accelerator to render in realtime --this somewhat reduces the final quality. Also, the game operates only in a few, fixed resolutions. This will not take full advantage of your 1280x1024-or-better display.
Also, you are probably going to want to find some way to force your video card drivers to produce 4xAA-or-better output, if that's possible. That would significantly sharpen up the graphics, and reduce the jaggies. Radeon owners, if they have cards or drivers that still support ATi's interpolate-more-vertices option (whatever it was called), may also get better results if they can force this option on.