Okami is a must-have title for anyone who has ever loved a Zelda game, a Clover Studio game, or any time-intensive 3D adventure game. The only people Destructoid would advise against buying Okami are those on the extreme left or extreme right of the "casual/hardcore" gamer divide. Okami for the Wii is too complicated and demanding for the Wii Sports crowd, while hardened "gaming gladiators" may find the title's requirement of skills beyond "excellent eye/thumb coordination" to be too much for them.
If you can handle a traditional adventure game that requires both a thirty- to fifty-hour time-sink and engaging in some actual, physical movement, then buy Okami on the Wii. It's one of the best games to come along in years, and arguably the best adventure game on the console, period.