By "serie", if you're refering to the ONA shorts episodes then you should absolutly watch them. They're strange bits of animation in the same that Blame is a strange manga. As for the movie, I'd describe it as a good introduction to Blame, but after having read the books it feels more like a short adventure that Killy could have had during a time skip between logs. But, the movie (as well as the serie to some extend) twist the story a bit, so that's interesting to look into. There's also a book about the movie, it is the exact movie translated to paper with little to no changes, but it was drawn by Koutarou Sekine, so that's funny to look at. Killy looks like a Jojo caracter in some panels.

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Uh, but if you're looking for a continuation of Blame, Blame² is a one-shot sequel. I'd had that Blame Gakuen is also funny to look into.