As history, I have no doubt that Tezuka Osamu's Buddha has taken some liberties with the narrative of the Buddha's life. As a piece of writing, however, this is an excellent retelling of the life of the Buddha. In the first volume of this eight volume series, the reader is given a general overview of some of the main characters and the background story. The Buddha himself only makes an appearance late in the book and even then, he's a baby. There are several narrative paths all of which converge by the end. The narrative flows smoothly and Tezuka does a great job creating between the reader and the several characters and even manages to make some of the more unappealing people rather nuanced and sympathetic.
There will be some people for whom the historical inaccuracies will get in the way of their enjoyment of the book. I would remind those people, however, that some of the most beloved works of literature are themselves gross distortions of history. Shakespeare's "history" plays border on fabrication, Mallory's Mort Darthur isn't exactly accurate and in fact literary representations of historical events have always taken a good deal of license with their subject matter. Yet somehow, there are a group of literary snobs who won't accept contemporary historical fiction and turn up their noses at all contemporary retellings of history. They have no apparent problem with their beloved cannon doing the same, but if contemporary authors do it, it's an outrage. Buddha is a literary retelling of the life of the Buddha and as such, it is most definitively not sold as nor intended to be a historical retelling of his life. It's an enjoyable introduction to this topic and has undoubtedly inspired lots of people to learn more about the life of its subject.