The artwork in some mangas is really good. Others not so good. I have read about half a dozen, and the plots did not make much sense so far as to the motivation of the characters. Perhaps it was just bad translation. The translation was okay for interjections (whizz! Pow! Kerplunk!), but other wise, it seemed just weird.
The only one that was memorable was Ozama Tezuka's biography of Buddha.... in SEVEN volumes.
It was good enough that Pope John Paul II suggested that he do another about Jesus. But there was apparently some problem about royalties or the Pope being senile and I don't think it ever got done.
Of course, there is a LOT more about the Buddha than there is about Jesus. Buddha lived to be 80 or so, and there were no missing years.
The Tezuka books are really good, because there are dozens and dozens of Buddha legends, written by a variety of people in a variety of languages over a very long period. None of the stories were written by anyone who made any claims about being divinely inspired, of course, and the sequence of events is vague at best. Miraculous acts are pretty rare, as Buddha was not into miracles. I recommend Tezuka's manga highly. The English translation is great.