There are lots of good things about this game. The music (at least towards the beginning of the game) is catchy, the controls are easy to learn, and gameplay is usually interesting. The graphics are great, and the expressions on faces are well done. The camera control is great. All in all, it's much better than Ocarina of Time.
This game does, however, have some problems. Getting around is really tedious. The world is big, but there isn't much there. So you find yourself changing the direction of the wind (do I have to play that stupid tune again?) and then putting the controller down while you wait out your long ride to the next island.
Some of the most annoying features of Ocarina of Time have been brought back to this one. There are some puzzles that really make you want to stop playing ("How in the world was I supposed to figure that out?"), and using the windwaker to perform tasks is a somewhat tedious process. Why don't they just have a simple command menu instead? There are a lot of things you need to do in the game that don't add to the enjoyment or the interest or the storyline, but just seem to be there in order to lengthen the gameplay.
There are some puzzles that need to be played over and over until you get them right. It's this way in just about every trademark game by Nintendo that I can think of (and, in my opinion, this is bad design). However, there aren't as many of these as there are in Ocarina of Time, and it's much less of an issue than it is in games like Super Mario Sunshine (ack!).
The fun, the challenge, and great graphics make this game a good one. Still, I had to stop every once in a while and play Metroid Prime instead, just to remind myself why I bought the GameCube in the first place.