Combat looks like total mess too (just mash buttans to win).
Okami derives a lot of it's combat mechanics from DMC1, which is unsurprising given that the development of both games were helmed by Hideki Kamiya.
There's one weapon focused more on cancelable techniques (Reflectors) versus another weapon type (Glaives) revolving around devastating charged moves, comparable to Alastor and Ifrit in DMC1. Okami deviates a bit from the DMC1 formula in that there's a third weapon type, Rosaries, that are all about ranged shots and Area of Effect sweeps. And instead of guns, a la DMC, Okami allows the player to equip another weapon to serve as a secondary, with varying effects depending on the weapon type (e.g. a Reflector equipped as a secondary allows for a timed block and counter move and Rosararies, depending on their make, offer rapid fire bead action or a shotgun-like burst all at once). It's a decent amount of variety, certainly more than your average 3D Zelda title, in which your core combat capabilities tend to be slash, jump-slash, and spin slash (Majora's Mask being the standout exception, what with the different forms; go go Goron Roll!).
And to further the Zelda comparisons, the primary puzzle solving pickups (treasures in Zelda games, brush powers in Okami) also play a secondary role in combat, with certain brush powers being extremely effective against certain foes; using a gust of wind against an enemy engulfed in flames will often blow them out, things can be cut in half with the brush slash, etc. Like Zelda games, it relies on varied and interesting enemy design to accomplish this. Unlike Zelda, the enemies are a little less linear, there's a bit more leeway in how to deal with them; skilled players might be able to slay a lot of demons in entirely different ways tthan they were intended, exploiting frame properties of moves rather than hitting the scripted weakness of the foe.
It's clear Okami combat was designed for people who liked action games, even if the difficulty was certainly not tuned for that crowd's typical preferences. There's a decent amount of depth, and the systems are fun to play around with. Even some content tries to push the limits a bit, namely some optional Demon Gate Challenges, though the horrible overabundance of recovery items makes the entire game a joke if one chooses to lean upon them at all. Like I said, difficulty isn't tuned for the action game crowd, especially not when in a Zelda-like you can carry 99 of every potion in addition to 5+ fairies. My suggestion, ignore items altogether and reset/reload if you would die rather than abuse the pouch of godhood or whatever it was.
People compare this game to Zelda series (at least the 3D ones), but all 3 I played (OoT, MM, WW) were interesting almost from the beginning.
It has an extremely slow start, especially the 10 minute intro cutscene that drags on forever due to the unskippable Banjo-Kazooie impression done at quarter speed. Even once free of that mess, the "tutorial" can be extremely boring, and the game only beings to pick up about 2-4 hours in, once the player has a couple weapons, brush powers, and is facing more than bog-standard foes.
After that, it picks up the pace a lot and plays far swifter than 3D Zelda games, if only because Amaterasu is way faster than (non-Goron) Link. Not to mention, the way brush powers are handled eliminates a lot of the annoying menu-swapping that comes with practically every Zelda game (2d or 3d, menuing is a huge deal, even before crazy shit like pause-buffering just-frame techniques). But be aware, the ending is
terrible (besides the final boss track).
It's a fun game in the middle, though, and if you enjoyed Wind Waker, you should certainly be able to have fun with most of Okami.