We all remember that guy from school, don't we? Hilarious, a mimicker par excellence, always ready with a crude joke or a bodily expulsion with which to puncture the balloon of academic pomposity. Complete tosser, obviously. Annoying, over-loud, over-brash, over-confident. A garish, merry-go-round of anti-personality that paid for its time on the earth with occasional flashes of hilarity. Do you ever find yourself wishing that you could meet that person again? Maybe go out for a dinner with them so that you can find out how little they've changed? No? Fair enough, move along. Yes? Deadpool is happening in a cinema near you. It'll be cheaper than inevitably picking up the cheque.

Deadpool is a superhero film. It will tell you that it isn't, but it is. It's based on a character most famous for appearing in X-Men comics, it has an origin story, people with super powers walloping each other through walls, a wisecracking hero and even a secret hideout. All these things make it a superhero film. It's just a superhero film with a lot of swearing, a lot of violence and a main protagonist who constantly tells the audience in fourth wall breaking asides that he isn't a superhero. Fox's decision to reboot and re-imagine the ultra-violent, ultra-sarcastic mercenary character created by Rob Liefeld and Fabian Nicieza, following his disastrous cameo – again played by Ryan Reynolds – in 2009's Wolverine film was much talked about when it was first announced. Having stuffed it up so royally in that boar's balls of a movie, what chance did they have of getting it right a second time? Well the good news is that they've got it about as right as you can get it. This is Deadpool as his fans have been clamouring to see him. Obnoxious, cynical, violent and rude, the film is a testament to the character's bizarre popularity. Unfortunately that's a set of characteristics that can only get a film so far before it starts to run out of steam.

Reynolds plays Wade Wilson, a special forces operative who discovers he has terminal cancer – wouldn't you know it! - right after meeting the love of his life (Morena Baccarin). As a desperate last throw of the dice he arranges to become the subject of an experimental treatment, administered by Ed Skrein's Ajax – Not even 'Doctor' Ajax, which surely should have set some alarm bells ringing - which kills the cancer, giving the patient healing powers as a side-effect and also hideously disfiguring him. Everything has its price in the super-verse, eh? This sets our hero off on the path of bloody revenge, taking in rogue X-Men, crack addicted old ladies, lots of shootings and, as Simon Bates used to describe them whenever you rented a video, “some sexual swear words”.

With these types of things it's a general rule that the simpler the set-up the better for all involved and that's certainly the case here. Keeping the plot tight allows for all manner of enjoyable dicking about on behalf of director Tim Miller. Slow-mo, flashbacks, cameos, jokey credits, the aforementioned fourth-wall smashing, Miller throws everything he can at the screen in order to keep things suitably buoyant, and for the most part it works. The fight sequences are nicely choreographed – if CGI heavy - and the zipping backwards and forwards in time makes the exposition feel pretty weightless. At certain points – the scenes in which Reynolds is assisted in the cracking wise by TJ Miller's Weasel especially - it all clicks together and Deadpool is as tight, rude and pacey as any fan could want. However, beneath this veneer of establishment-baiting edginess lies an extremely conventional, and rather boring, heroic narrative. One that fails to take any risks messing with the beats that this kind of film always hits. Deadpool ends up in the same position he generally ends up in in the comics: a fun character marooned in an environment that he's free to mock, but can do little to alter.

Make no mistake though, this film is going to be a massive hit. You could almost hear the Bash-Street-Kids-style hoorahs of relief from secondary school playgrounds when the 15 certificate was announced, meaning that it's target audience – sixteen year old boys, basically – would have access to its profane and forbidden delights. Indeed, looked at in recent company, Deadpool could be seen to be a part of a sub-genre. The Kick Ass films and the recent Kingsman: The Secret Service both have a similar line in vulgar heroism (although thankfully Deadpool is nowhere near as reactionary and desperate as the latter).

Deadpool's delights are there for all to see. It's enjoyably throwaway, well performed and for the most part well executed, but this only goes toward making its flaws more frustrating. It isn't very funny, for example. Something you'd have thought was a given with such a heretical main player. And what does it matter that the main female character explicitly refuses to identify with the role of damsel in distress if she's captured and the male hero's job is to rescue her? Indeed Deadpool spends a good amount of its running time telling us that it is something that it isn't, and no amount of fourth-wall breaking extremity can disguise that fact that what it is is an extremely conventional superhero film, right down to the pointless fan-service cameos from X-Men Colossus and Negasonic Teenage Warhead, and a main villain who appears to have absolutely no motivation whatsoever. “Surprise!” our protagonist exclaims during one violent dismembering, “This is a different kind of superhero story.” Sorry, Wade, I just wish that were the case.

Deadpool is out in cinemas now