This would have been a great game if the Massively Multiplayer service hadn't been cancelled. However, I believe it is still a good game. Some of the puzzles are a bit time consuming, but I found it less frustrating than the average FPS. Another thing to note is that it is still possible to play online using the fan-run UntilURU servers, see: http://plasma.cyanworlds.com
The graphics are certainly stunning, but require a very high spec computer to reach their full potential. Definitely worth it for any Myst / Riven fan.