Endless Ocean has something for both casual gamers who want to have a relaxing time and dedicated completionists.
The Bad: Terrible human models; barely a real "game"; cheesy new age songs.
Endless Ocean is an underwater diving simulator and as such it does a good job in accomplishing its first "directive": to deliver some relaxing undersea exploration experience without lots of "whys" and "hows" for the casual player. Those who like marine biology or just want to have a nice ease playtime will be easily lured into it by the nice representation of fishes, big mammals (including whales and seals), birds, crustacean and pretty much every other possible sea-related life form.
Of course, the Wii is far from being a graphics powerhouse by any means but well-choosen textures provide a nice final result in this front--except for human models, which are just empty plastic shells. -.-
More than that, the game even shines in the memorable occasions it offers you the opportunity to face--and interact with--huge beings like the Atlantic Northern Right Whale or the Giant Squid. (Achieving this degree of epicness by creating some truly breathtaking moments without cheap graphic tricks is something Arika should be proud of.)
The objectives in the game aren't really compulsory, so you'll get several "quests" to perform every now and then--people asking for guided divings, fish photos for magazines--but they can just be ignored and you'll be fine anyway. You can't die either, so it's totally on the easy side to fit the casual "Blue Ocean" (no pun intended) market Nintendo aimed so well in this generation of consoles.
On the other hand hardcore gamers tend not to dig Endless Ocean for the very same reasons, but if you're the completionist type there are plenty to unlock and uncover (and there's a good chance you'll feel compelled to do so): a fauna encyclopedia to fill in (and creatures change depending on where/when you dive), a map to unfold, historic relics to scavenge, secret places to find, a major local legend to clear up (and ultimately "beat" the game) and more.
It's easy to mistake Endless Ocean for another careless shovelware Wii release, but one couldn't be more wrong in this case since Arika took the hard route by really trying to offer something for everyone--and succeeding.