I went to a free screening of this last week. I agree with Chris, one of the best films I've seen this year as well.
Although the characters were entirely "real", I found the way they handled some of the situations were a tad over the top.
Steve Carrell does a great job in a more 'serious' role, and the actress who plays Olive, the little girl, delivers a performance that Dakota Fanning could only dream of.
The exchange between