Very rarely will you see a successful show randomly shift its focus, but such is the case with The Big Bang Theory. The Leonard and Penny relationship, that paralleled Ross and Rachel from Friends and Sam and Diane from Cheers in ways, dominated the first season, but has since been replaced with the Sheldon and Penny relationship. Zero sexual chemistry between the two, but I do not think you will find anybody who would argue that such was not a change for the better.
I liked this episode for the most part, but Howard went a little crazy here mentioning strippers and his testicles in the span of three minutes. That kind of lowbrow humor is beneath The Big Bang Theory, but otherwise another fine episode of the program.