I have to admit, I got a little bored with this by the (over cute) end, but I didn't mind this and I think I will watch it again when I'm not as tired as I am at the moment, see if it makes a difference.
I liked the trio of Krysten Ritter, Kate Bosworth and Rachel Bilson. Yes, they're all a bit pretty, and Krysten in particular does not look the part of an exhausted single mum, but I liked that they weren't played as perfect, and, ending aside, being a single mum wasn't glorified as being a wonderful thing. Krysten's Kim really struggles here and it isn't all roses.
The worst one was the fake Australian ex. His accent was shocking and the phrases cringeable. He also wasn't believable as someone such a beautiful girl would go for.
Jason Biggs is barely in this, surprisingly.