This episode is brilliant. I always look at the BBT episodes in two parts because there are usually two stories in each episode. This one had the three guys going on camping and on the other hand Penny and Sheldon.
Now, I must admit the guys' story wasn't as original or as funny as we are used to. But, there were some very good scenes (especially the one when the three of them lie on a rock and tell stories and fantasies about themselves).
But again the highlight of the episode is of course Sheldon who once again outdid himself. From the very first scene (Sheldon's log) to the very last (when Penny and Sheldon sing soft kitty), Sheldon is hilarious. My personal favourite is at the hospital where Sheldon tries to comfort Penny.
Regardless this is a very very good episode that made me laugh out loud. I do find however one flaw to the show (in general). It does lack the story-telling of a season meaning that the episodes are one of their own and don't add up to a bigger picture. There are no stories that could help character development. Having said that, Big Bang Theory is a very well written show which I believe will go on into a 4th and a 5th season, maybe more.