husband & I went to see "It's Complicated" on our wedding anniversary. I think it helped us to feel even more smug at being married to each other for so long. I know people have been down on Alec Baldwin for his bad behaviour to his daughter (although which parent leaked that phone call to the media and put it on the internet?) but if he was able to do as good a job as I felt he did in this role, then he 'gets' it. His character - is a total "poohead", as easy child would say. Charming, persuasive, manipulative - you can see (Meryl Streep's character in the movie) why she married him in the first place. You can also see why she divorced him.
Frankly, I liked the film. If it had anybody else, not Streep & Baldwin, I might not have liked it so much. But they carried it off well, with 'layers' as I call it, those added depths that make the characters more 3-dimensional. At times Baldwin's character's behaviour does tend to be a bit farcical, and I did find the appearance of Steve Martin to be very disturbing (WHAT has he done to his face? He looked like he was wearing a Steve Martin mask) but once I forced myself to ignore the plastic shine and cute eyelashes, I was able to see into the very sympathetic treatment of his character.
It isn't a brilliant movie (not like Doubt, which husband & I saw on our anniversary the year before and thought was fabulous) but it was an enjoyable and moderately thought-provoking bit of fun.
I haven't seen the others so I can't compare.
I hope this helps.
Marg