All my boyfriends have been incredibly emotional - some of them even more emotional than me.
My current BF is probably the most emotional of the bunch. He cries everytime he picked me up or drops me off at the airport (we have a long distance relationship going atm) and once he even burst into tears totally out of the blue the day before I left to come back to Hawaii because he said he knew he was going to miss me so much. Sometimes when we watch documentaries on TV - particularly involving war and/or children - he tears up.
I like it, though. It's such a contrast because he's very masculine in every other way... just not with me or when we're together... especially alone together.
OMG - the cutest was when he dropped me off at the airport a couple months ago and went into work afterwards. His boss stopped him to talk to him, and I came up in the conversation. BF totally broke down in front of his boss because he was so sad about my leaving... said they both ran to their respective offices and never spoke of it. ROFL. Besides that event, he's typically a stoic in front of his coworkers/people he doesn't know well... unless I come up, apparently.
I guess I'm rather used to it because the men in my family are quite emotional. My Dad and his brothers (all big, burly guys) always cry when they have to say goodbye to each other after they have a reunion, etc.
Of course it goes the other way(s), too. BF can get very angry, and I know it. When he's happy, it's very noticeable... as Tink said, he wears his emotions on his sleeve with me.