Pegg and Frost share credits as both writers and stars, playing two British sci-fi and fantasy geeks (not a huge stretch for either of them); whilst there are glimpses of the infectious chemistry seen between the two on screen before, here it never fully ignites, feeling like a somewhat shallow imitation of what the duo have previously offered. Seth Rogen is an actor I can take or leave, and his performance as the voice of the titular alien fugitive does nothing to sway me any further either way. It works, but Rogen is never outstanding and at times feels as though he's simply going through the motions. Kristen Wiig is fine in support, and Jason Bateman's antagonistic secret service agent generally works well too, although a character shift in the final act feels like a stretch too far. Bill Hader and Joe Lo Truglio's junior agents are less successful, but by no means terrible providing a few minor chuckles throughout.
Script-wise, Paul paints much broader strokes than Pegg and Frost's previous more highly regarded films, which may widen its appeal but also makes it feel much less sharply crafted. The writing is at its best when paying tribute to science-fiction films gone by with enough references to keep even the most ardent film buffs happy - a voice cameo by a certain alliteratively-named director is a particular highlight - but elsewhere lazily falls back onto the blunt and heavy-handed. Easy targets such as the Christian right and intolerant rednecks feel beneath the British twosome considering their more finely honed previous comedic works.
Ultimately, there's enough to enjoy within Paul to make it worth a watch. The story is episodic and at times unfocused, but managed to hold my interest throughout. If you expect Paul to do to sci-fi what Shaun Of The Dead did to the zombie and horror genres, or what Hot Fuzz did to action and buddy cop movies, then you'll undoubtedly come out disappointed. But go into Paul looking for a lighthearted sci-fi comedy that will entertain without taxing your grey matter too much and you could do a lot worse.