I will disagree here with most, Why rush. Seriosuly it isnt like a Bag or a pair of shoes that if you dont like you can just return.
Dont feel rushed, take your time and if you dont feel it there is no need to buy there merchandise. It doesnt matter if he is a nice guy or not. He could be a great guy, just not a guy for you.
Most of the stories posted here are people who werent sure, but married anyway and are happy. I doubt you will get too many stories from people here who didnt know and married anyway and found out later it was the wrong decision.