This game is visually stunning, mentally engaging, and is even more immersive than any Myst game before. Its puzzles are far more integrated than those in Uru or Myst III, and thus seem much more natural. It also has a tool for taking (and annotating) screen shots, and for “zipping” to different locations, as well as an integrated help system for if you get stuck.
The Collector's Edition is better still, as it has far better (and more artistic) packaging, as well as an extra DVD with “making of” footage, and a whole collection of songs from the soundtrack (these alone make it worth the extra you pay- the music is brilliant!), and, strangely, a pack of playing cards…
If you're wondering whether or not this game is worth buying, take my advice and get it- and if you're wondering if the Collector's edition is worth the extra cash, trust me- it is!
(It is worth noting that this game is available only on DVD, and takes between 4 and 8gb of disk space- you have been warned! ;) )