The arcs that truly would be worth watching is not adapted in the anime and thus you miss vital character development and story. The ending of the manga will solve most of the questions about the story and characters which is something you cannot get out of the anime version.
HOWEVER, if you're not keen on reading and would rather watch I would recommend watching the anime up until the last arc in which you can decided whether you wish to read the manga or not as the anime in itself is pretty good.
Since the story of the anime is incomplete at best you'll merely get an introduction to the show in the anime.
The characters and their development are good, but due to character development taking place after the anime you cannot witness that in the anime which means it will be lacking. Not only this, but the power of the characters and battles won't be at its peak either, but the battles in the anime are still very enjoyable
It's a great show, but it lacks vital parts of the manga. However I would definitely recommend it if you're not into reading manga
