I think the writers wanted to extend the build up of Leonard and Penny's relationship a little longer, but then decided to just get on with it. It felt a little rushed. It was funny to say the least, but an event that has been anticipated since the beggining of the season came off as a little underwhelming an awkward. I don't know if this is just me and my oponion of their relationship, but It just didn't feel "right" like I thought it would.
Regardless of the plot developments, it was still hilarious.