The anime isn't that bad, but for someone that has read the manga first, it's hard to stomach all the significant changes. Turning most of the villains into big bad monsters was pathetic. Things are a lot better when it's superpowered human with inhuman skill against superpowered human with inhuman skill. Adding mutating monsters to the mix does not work well.
The music was generic. The animation wasn't perfect. I noticed too many still shots being used and the battles were repetitive. Then again, the manga battles were also repetitive as well as predictable in which the battle always (usually) ended with the good guy cutting down the bad guy or maybe Kyo/Kyoshiro activating some lost power and godmodding the villain.
It was nice to see Yukimura come to life. He's just as hilarious than he is in the manga. Demon Eyes Kyo is the generic badass, but still the badass and Kyoshiro might seem to be a weakling in the beginning, but later on, he's almost more badass than Kyo himself. Yuya is the damsel in distress as well as a chick with a gun. Anime Sasuke came out to be a wimp sometimes whereas Manga Sasuke was always a short little badass.
The anime isn't that bad. Like with most series, the manga is a whole lot better.