First Hit: An old idea with varying results.
The idea of people inhabiting someone else’s body is old and there are at least a ½ dozen films around this premise. This isn’t necessarily a bad thing unless there is nothing new in it.
As with all the other films like this, while they are in the other person's body they learn something about themselves and the other person all before they go back into their own body. Nobody stays in the other person's body.
Therefore how much is there to tell about this film? Some of the jokes are out-loud funny. Some of the bathroom humor could (flying baby poop in the face) could be removed and not affect the overall film one iota. Nor did I find that Mitch Planko (played by Ryan Reynolds) to be very believable. I didn’t think he fit being a lorno (light porno) film star, nor did I think he was much of a ladies man if he spent weeks trolling Lamaze clinics looking for a sex partner.
I thought his gross and crass language while being around his best friend Dave Lockwood (played by Jason Bateman) and his wife Jamie (played by Leslie Mann) and their children to be more than required as a setup to how different the guys will be when they embody the other person.
For them to transfer brains/spirit, they pee into a fountain, the lights go out and then the next morning they become the other person. Funny it took them until the next morning to discover they were a different person, because when they reversed the spell it was almost immediately.
There are numerous funny bits that each get to perform being the other life which made the film watchable.
Reynolds was, for me, more OK as Dave than his original character Mitch. Bateman was also better as Dave than he was Mitch. And neither one of them felt very spot on as the other, only caricatures of the other person. The film makers made more of the physical scenes being reversed than hold true to the real characters being reversed. Mann was very good as Dave’s wife; however it was very unrealistic that she wouldn’t have caught on that her husband Dave wasn't really Dave but someone else. They were nowhere near the same people to her. Jon Lucas and Scott Moore wrote a occasionally funny script. David Dobkin didn’t do much to build some depth to the characters while relying on obvious, and at times, humorous scenes.
Overall: This film was good enough for the moment and immediately forgettable afterward.