I'm not sure there's anything to buy into...or hype...as far as I've seen. I just have always liked his acting and from watching Luther, know he can play the troubled detective very well, which fits the Bond persona to a T, save for being upgraded from detective to ridiculously super secret agent man. I saw him on a list of actors that'd be good and/or interesting to play the next Bond and he was on there, that's all. If there's any 'hype' surrounding him, I haven't heard it. (The word hype is so overused recently...like ridiculously so, and it seemingly came out of nowhere...but...I digress)
I mean, I pretty much am open to anyone who isn't a fucking teeny bopper, angsty little shit. Those types are just rampant in Hollywood and it seems the 'in' thing to do these days is make a character young and dumb. That said, I really hope the minds behind Bond wouldn't let that happen but I don't put anything past the movie biz.