Well, I think that this is best episode in season 11. They must'v read my review of episode 17, where I talked about need for guest stars, shooting on some new location(s) :-) That part in cabin was hilarious, and girl's party was great fun too.
Now, probably most interesting question is in which direction Sheldon goes. Obviously he is getting less nerdy, some social skills blossom . Some people probably don't like it, but I think that it is good way, and show can be very funny still, if not funnier.
Indeed, hardest part in so long serials is to create something new, while keeping basic idea. This episode was that. Nice work Chuck and Co. :-)