This was an hilarious installment, probably the best one of this series. The Sheldon-Penny combo seems to be working pretty darn good. The rest of the cast has also pitched in well, especially Simon Helberg's character Wolowitz. The portions where Sheldon's friends suspect him of having an affair with Penny and the pun-intended dialogues were a laughter riot. Certain other parts such as the 'AFK' and 'Oh I see' lines were silly, nevertheless the were funny for the moment. Leonard has been downplayed this episode. And as a forum post says, he doesn't seem to care about Penny anymore. Though there wasn't a concrete story this time around, it's good to see that the writers are restricting the genre to strictly comedy. It was huge relief to see Sara Gilbert get less screen time, though she did a good job this episode. However, when she gets into the main cast, it really changes the way you look at the show. And that definitely doesn't look pretty.
This is good experiment, and the way I see - this show will only get better.