Let me break this down for you:
1) Tony Stark is extremely experienced. He knows what's up.
2) He has an ego based entirely upon his desire for unimpeachable excellence. He would absolutely make sure you spent the next decade bragging about how good he was in bed.
3) If for some reason you weren't satisfied, he would create a DEVICE just for your pleasure. And it would WORK. REALLY WELL.
4) The whole experience would be fun, surprisingly emotional, and glamorous.