Not perfect but getting there
The first Endless Ocean was a fun game if you played it knowing it wasn't your typical game. It was more of a "Learn About Fish" game then an actual game. Blue World though adds more to the gameplay side of things that will make fans of the first game want to play the sequel. The addition of danger, running out of air, and using a pulsar gun are just a few things that make this game more interesting and entertaining.
Being a huge fan of everything that is ocean (i own a saltwater retail shop) , i can honestly say that the scuba experience in Blue World is pretty close to the real thing. The way hear yourself, the way the fish act, and even the way the rock formations and coral are very realistic. The amount of fish, coral, and inverts you see are incredible and the amount of information you can learn from just clicking on one of them is great.
Again this game is not for everyone, if you have any interest at all of scuba diving, or you enjoy fish, corals, and inverts, i would say this game is a must play. The graphics are not as good as the 360 or PS3 but for the Wii they do a pretty good job.