I've spent a good few hours with it already and so far i'm quite impressed - there isn't much to the gameplay, but exploring the underwater depths of Kisira Atoll is quite addictive - the lighting effects are great, and all the marine life animation is done really well. The story is set in a Marine Research facility in Polynesia where you play a journalist reporting on the disapearance of oceanographer William Graber - in your attempts to re-trace William's footsteps and understand his research you are given use of one of the facilities submarines. At first only a small area of the Atoll is explorable, but by discovering and re-powering sonar navigation buoys new areas are opened up - as you progress you unlock new abilities for the submarine and log entry's left by William. Theres a huge database of marine creatures and relics for you to fill in and doing so earns you money that can be spent on batteries for the sonar buoys and other equipment.
Overall i'd reccomend this if you're looking for somthing different, it looks great and is really relaxing plus the adventure storyline, side-quests and trophy support should be enough to keep you entertained.
Here's a few shots from the game (you can take pictures when you unlock the submarine's camera feature);
