My stepfather adopted me when I was very young. In my early 20's, I went on to find my birth father and I was sorely disappointed with the experience. I thought I would be able to be friends with this person, but he was a horrible human being. I realized I had been better off being adopted by my less than perfect dad, I'll leave it at that.
I would say for most, it would be a good experience, but to go in with eyes wide open. You don't know this person. In many instances they are good people - how unselfish and loving to give a child a chance at a better life if you can't care for them... but at the same time, some people are just bad people.
If I had to do it again, I would have run a background check or found out more information about him in his present state before proceeding. I was naive and thought that perhaps he had changed since he was young when I came along. He not only didn't change his ways, he was 1000 times worse.
I suppose I am jaded by my experience, but my belief is be very careful and have no expectations, that way you won't end up disappointed.