If you don't have plans to see this movie, you can check the spoilers here and then come back.
I dug this movie in large part because it defied my expectations of it. I went in not really knowing what I was getting other than knowing I liked the cast and it had good buzz; early on, I settled into thinking I'd be watching a decent feel-good flick about families coming together, overcoming the adversity of differences, etc., but this film is insidious in that way, as things are not as cut and dry as they appear from the onset and that was what I really sunk my teeth into. Indeed rather than being about coming together or overcoming anything, this movie showed how some challenges can be insurmountable when it comes to interpersonal relationships, people don't always live up to your hopes for them even if it seems they will at first, and yet in the end there is still the lesson that those who truly care about you will find a way to make it work. There is positivity in this story and just enough feel good, but you come to it through a filter of refreshing realism, not to mention an entertaining script that makes the drama and angst go down easier with healthy doses of wit and some great performances. Even amongst a pretty much uniformly strong cast, I'd say Mark Ruffalo stands out as the easygoing sperm donor rediscovered by his teenage kids who at the onset seems the ideal cool guy, but has so much more bubbling beneath the surface; trying to figure out whether or not Ruffalo's Paul was a decent person, a heel or somewhere in between was probably the most engrossing part of the movie for me. Annette Bening also does a great job as the more pragmatic and neurotic of the two lesbian mothers in the non-traditional family the film centers around; she brings both fire and realism to her portrayal of an imperfect woman doing her best not to lose her family. As the third point of the adult ensemble triangle, Julianne Moore is excellent (as she generally is), bringing great chemistry and subtle comedy to her part. The titular kids really are all right (forgive me for that) as both Mia Wasikowska and Josh Hutcherson prove capable of hanging right in there with their more experienced castmates and propelling things forward while getting some great lines in. I'll only take points off for the dismount in that the first two thirds of the film are far stronger than the final half hour or so, where after the big revelation things seems to grind and go on longer than necessary, with a conclusion that didn't fully satisfy me after a great set-up.