The girl was fabulous, as were Jeff Bridges and Matt Damon, but I think the key was the writing. Their semi-stilted language was very colorful and did a great job of re-creating the Old West. All the character actors portrayed the toughness of the Old West very well. I prefer Jeff Bridges to John Wayne, but wish they could be in a movie together.
What a balanced, likeable couple Steve Carell and Tina Fey make. Both hilarious ad-libbers (witness the trailer) and endearing as a pair of suburban wanabe-great-parents. Also enjoyed the supporting cast -- Mark Wahlberg especially (please put a shirt on...) All great and make this a very entertaining romp.