well yeah he does like you.. unless there's any negative, significant details he's left out. why did he fail to see you twice already?
I know the question is whether he likes you or not.. but I kinda agree with what everyone's saying about pothead's. The relationship hasn't started and he's already unreliable. Just think if further into it you won't mind. I know you probably think 'I can change him'.. it is highly unlikely that you will. Weed is a drug.. and it's what he'll turn to (if he doesn't just keep smoking it anyway) when you annoy him. Weed can't bitch or whine or complain or make him give a shit. So it'll probably prevail over you. The only other way it could go is if he stops while he's with you and goes back to it when you've split, or he'll just go behind your back and do it anyways.
Good luck, I hope you make the right decision.