In some ways, the plot of MW is standard 1970s-era manga stuff, such as a government cover-up of a secret military project – a device which would get even more play later in Katsuhiro Otomo's Akira.
But the themes of Roman Catholicism and homosexuality are rarer, especially in the context of the rest of Osamu Tezuka's career.
MW is of added interest now because, first, it has only become available in English in recent years from Vertical. The translation by Camellia Nieh is pretty good – much more fluid than some poorer manga translations, such as that of Moebius and Jiro Taniguchi's Icaro.
Second, a live-action version of MW came out last summer in Japan, although it got bad reviews. As is often the case, it's better to stick with the original comic.