I'm impressed with Barney's growth as a person, owning up to Nora about what he did instead of running away or blowing it off. NPH is a great actor, and makes even a morally disturbing character sympathetic.
I assume Kal Penn will only be on the show until Harold and Kumar opens, so maybe another week before he dumps Robin (and I hope he does it instead of Robin dumping him).
I know this is an ensemble show, but I wish they would have dropped the Lilly/Marshall/Ted b-story and focused solely on Barney and Robin. They could have fleshed out a lot more with that extra 10 minutes.