A very nice break from the typical First Person Shooters!
Graphics: One of the best graphic systems I have seen on the Wii (The best I have seen is Super Mario Galaxy). The rays of the sun coming through the water shine bright, the bubbles from deep-sea mini-volcanoes, and the fluent movement of the Humpback Whale as it swims through the abyss.
Music: I personally find the music here quite refreshing. It isn't the type of music you would find in a game, in comparison to, let's say, a skateboarding game. This game is supposed to be the smooth, relaxing type - not the tense, action-packed, "rocky" type of game. With that said, you won't find punk rock or rap in this game, but several (all but two or three) ambient music, emphasizing chords and major or minor tones.
Gameplay: Now, this is the section that is quite hard to describe, yet so easy. Simply put, you dive around a large map, either doing whatever is to your hearts intent, or completing various designated tasks (given to you via your "E-Mail" device), such as being a diving guide, following a rare species to see it's migratory route, searching for artifacts, or taking pictures of different designated species of fish.
Controls: With the Wii remote (the only needed equipment), every provided button is used (excluding the up and down arrow on the directional pad at times). You swim by either aiming the wii remote at a location on the screen and holding "B" to swim in that direction, or aiming the wii remote at a location on the screen and pressing the "-" (minus) button once, to do a sort-of "Auto-swim" in that direction. The rest of the buttons are quite self-explanatory once you play the game.
Replay-ability: I cannot much comment on this matter, for I have not finished the game yet, but I would expect the hardcore gamer to not find fun in replaying the game, and the casual gamer to thoroughly enjoy replaying the game.
This game is not at all linear, but I tend to stick to the storyline. For me personally, the game does go slightly slow for me (being the FPS and online multi-player type), but for the non-casual gamer, this game could be the fun break from typical life (and gaming).
Overall, I would much recommend this game to the casual gamer, but be sure to rent it before-hand to make sure it is the type for you.
Thanks for reading,
TheDarkPenguin