Paul is the sci-fi version of Shaun of the Dead and Hot Fuzz. Like the other two, it was written by its leads Simon Pegg and Nick Frost, and is filled to the brim with references to all the best films of the genre that came before it. But unlike the other two, it felt like they were trying too hard to recapture their past success and just ended up beating a dead horse. The spoof/parody/homage formula they created was intriguing in Shaun of the Dead, perfected in Hot Fuzz, and has now become washed up in Paul. (Or maybe I'm just not as big a sci-fi fan as I am an action fan.)
There are jokes aplenty in this movie and I laughed more than my fair share for a comedy, but for some reason the film just didn't engage me. The character of Paul had too much Seth Rogen in him, the road trip adventure felt bland and unexciting, and for whatever reason I never found myself caring about what was happening. The movie is fine as far as entertainment goes, but I expect better from them. If it seems like I'm harsh on the movie, it's because I know those two can do better. And I hope they do on their next project.
IMDb link: http://www.imdb.com/title/tt1092026/