Stupidly nonsensical, yet somehow still boringly cliched OK You don't expect Hamlet going into a Marvel movie, and to be fair some of the set pieces work really well. Matt Smith strikes the right balance as the foil, ands for once Jared Leto is also reasonably understated, wisely relying on the effects and makeup to do the donkeywork. That about wraps up the good news.
Where to begin with the bad? I think the pseudo-science. Oh the pseudo-science. I get that there has to be a certain amount of gibberish and fudging for the origin story to work, but it seems like the writer only heard about DNA third hand from somebody describing a particularly dodgy episode of CSI.
I found myself constantly thinking (and quite possibly muttering) "no they can't", "no it doesn't" or "no it wouldn't" throughout the first third or so of the movie. The very first line uttered was "vampire bats are tiny but they can take down an animal 10 times their size". No they can't. And upon delivering this pearl of "wisdom" our hero cuts open his hand and thrusts it into the mouth of a cave full of them, which immediately awakens these apparently literal vampire bats and brings them flying out in exactly the kind of a feeding frenzy that they absolutely do not do, like some sort of flying piranhas.
The plot, once it gets going, oscillates between tired rehashes of age-old cliches and things that make no sense whatsoever, sometimes both at once. For example (*spoiler alert*) when his best friend inevitably becomes an inexplicably malevolent version of Morbius, there is also no explanation of how this was achieved without the same harrowing series of experiments and gradual changes under controlled laboratory conditions that Morbius underwent. When the clichéd pair of sick children living in the hospital undergoing gruelling daily treatment (and of course being bullied by healthy children for no apparent reason) grow to manhood, it's never explained how the pair of them survived even though it's explicitly stated that many others before them died. When Smith as the newly powered bad guy picks a fight in a bar by chatting up a Tough Guy's girl and insulting him, it's never explained how the Tough Guys in New York still haven't learned by now that every freak that does this has super powers, since at least 1986 when Jeff Goldlum did it in the remake of The Fly.
So yeah, no.