Been with 3...one recently. It's cool if you are patient and take time with them...you have to remember that it can be a very special thing to some women.
That said, it can be frustrating to a guy as well. The first one I was with was so tight it literally took months before I could put it in fully, and other than telling how much it hurt, she was about as exciting as a coffin with a hole in it...but in all fairness it was a long time ago and we were in our late teens. The last one though (also 24), was a fast learner and we had some amazing sessions- she was incredibly flexible, very creative, and truly uninhibited. Everyone is different...