It all depends on the context and other behaviour.
Holding hands is a visible sign of affection for both you and everyone else who sees it.
So a clue to how he feels is not whether he holds your hand but when.
If he holds your hand in front of his friends, his or your parents or his work colleagues, it's a good indication that he is in to you.
He is essentially telling those people that you are together and he doesn't mind who knows about it.
Similarly, if you are holding hands until his friends appear and then he distances himself from you, that could be an indication that he is not that in to you. Don't panic if this has happened though, it could just mean that he's not ready for people to know about you yet. Only worry about it if he says he's ready to be your partner and then stops holding your hand when you're in company.
Holding hands needs to be put in to context by looking at his other behaviour. If he's always trying to get you to go further when you are kissing but won't hold your hand in public then it's a bad sign.
If he pushes your hand away when you try to hold his, it's could be a bad sign but not all men like holding hands so don't read too much into it if he's not really in to touching even when you're not in public.
So consider what he's like when you're on your own.
If his hands are all over you but he doesn't like holding hands in public, he just wants to hook up.
If he doesn't like holding hands but keeps them to himself when you are alone then relax, he's probably just shy and is in to you.