I can't really say why I liked Tully as much as I did, because they're things that pretty much need to be part of the viewing experience. It does a few things that are definitely tropey, but it does those things in a way that really only enhances the things it's been trying to say before those tropes become a factor.
That's legitimately all I can really say about it as a movie, other than the fact that Charlize Theron is an incredible actor and if we can somehow find a way to distill her talent and pollinate drama schools with it, we should be investing in that program post-haste.
Also, as much as Ivan Reitman has given the world of filmmaking and film lovers alike, Jason Reitman is definitely his biggest gift. Very well written by Diablo Cody as well, making this my #1 Theron/Reitman/Cody film over Young Adult. And I loved Young Adult.