The anime had a lot of potential due to the material it works with and the universe it is in, but the writers did the favor of sticking it in the ass.
The anime starts off silly, and without a very interesting story. When he finally goes into an interesting story (Kurata's arc), it quickly gets bad again, which is why you see the pattern that the scriptwriters have anxiety. Every time a new problem appears, a new evolution or improvement suddenly appears and they immediately solve the problem. The animation is sometimes terrible, in addition to the constant change of voice actors.
If you're olden than about 6, you'll find this pretty freacking stupid and frustrating to watch.
