Blessed as they are with an easy-going onscreen chemistry that appears as natural as the dew and the springtime, Nick Frost and Simon Pegg have become as inseparable as they are celebrated, with sleeper hits the likes of Shawn of the Dead and Hot Fuzz gradually attaining the status of comedy classics, and proving their small-screen debut, cult hit Spaced was no fluke. Yes, despite the on-screen constancy of the ever-present dynamic duo forming the bedrock of each of those previous outings, slacker comedy Paul marks the first time the pair have collaborated behind the camera.

Spaced was penned by Pegg with co-star Jessica Stevenson, while both Shawn and Fuzz were scripted in collaboration with longtime directing partner Edgar Wright, both of whom are absent entirely, leaving Pegg and Frost, who also star, to their own devices for the first time. It’s perhaps for this reason that for much of the opening act Paul struggles for definition, the pair perhaps not wishing to sour the endeavor during its early stages by rejecting any idea the other might put forth.

Indeed, the preamble through San Diego’s Comic-Con, the first stop for best buds Graeme (Pegg) and Clive (Frost) on a road trip of famous Midwestern UFO sites, is remarkably tame, deifying its geek patrons as opposed to finding reason to lampoon them. It’s a nice gesture of appreciation to fans – and acknowledgement of the hand that feeds – but it reeks of playing it safe by two men who most definitely are capable of much, much more. Much of Paul’s awkwardness in fact comes from a sheer lack of conflict, the only friction between Graeme and Clive (or “the writer Clive Gollings” as he prefers to be known) seemingly an unspoken contest to see who can be the more amiable?

Then, with your patience just beginning to be tested, the man of the hour appears and the film finally kicks into high gear. A stoner, slacker, little-green-man-with-a-heart-of-gold Paul (voiced by Seth Rogan) is a whirlwind of mirth and chaos tempered by gentle warmth and a comic trajectory perfectly aimed dead center of suitably adult without ever being needlessly gross. Hightailing it across country, pursued by Jason Bateman’s agency stooge and accompanying men in black, Paul takes up residence in Graeme and Clive’s motor home and commandeers their vacation towards aiding him phone home and wotnot.

With it’s innumerable silly similarities to E.T., Paul stands as yet another gigantic blowjob to Steven Spielberg, which along with Super 8 seems all the rage right now. But where as that movie went to great lengths to celebrate the kind of heart swelling wonder that was the man’s bread and butter, Paul is far more tongue-in-cheek about the whole thing, a sentiment hammered home by a tiny sequence that stands as perhaps the finest stunt-cameo since Bill Murray in Zombieland.

Every moment Rogan’s pint-sized spaceman is on screen Paul is a riot. The problems the movie has are not inconsiderable and lie just about everywhere else. The much-needed conflict between Graeme and Clive, finally sparked by Paul’s arrival just doesn’t make sense. Wouldn’t a science-fiction author currently embarked on a roadtrip of historically significant alien hotspots be more excited to meet one? The bromance the film implies Paul might be interrupting simply isn’t earned the way it is in Pegg and Frost’s previous on-screen outings together.

Similarly, Paul’s merciless mockery of Kristen Wiig’s god-bothering creationist, who winds up tagging along, just seems like such low-hanging fruit. Jason Bateman is miscast as the pursuing agent with a hidden agenda, the payoff of which is equally underwritten. All of this is to say nothing of Sigourney Weaver’s extended and pointless cameo, most of which takes the form of a voice on the other end of a phone, and which only exists seemingly to climax in the most pointless, redundant, done-to-death-a-thousand-times gag in all of science-fiction spoofing.

Helmer Greg Mottola has previously demonstrated in both Superbad and Adventureland that he has a firm handle on both slacker sass and rose-tinted nostalgia, and perhaps a more stringent approach by him would have aided in the narrowing of focus and the streamlining of the script. The film is called Paul, who single-handedly elevates the movie out of the muddled mediocrity in which it might otherwise be mired. But this is Paul and Friends, none of whom, sadly, are anything like as layered or entertaining as the eponymous little fellow. Which is the real shame.

Special features feature Pegg prominently, with his natural comic gifts on display in such segments as Simon’d Silly Faces and Hilarious Bloopers. Feature commentary and The Evolution of Paul showcase yet more evidence of that all-important chemistry. Best of all is Who The Hell is Adam Shadowchild, a brief expose on the puffed up fictional author who provides the ammunition for one of the movies better running-gags.