The release of this sibling sequel to the original Trainspotting (1996) 20 years on reunites us with familiar associates Renton, Spud, Begbie and Sick Boy. All are older, but... any wiser?

Mark Renton (Ewan MacGregor) escaped at the end of Trainspotting having nicked the loot from a drug deal and legged it; we learn that he's been living in Amsterdam – swapping his heroin habit for miles on the treadmill, but things aren't all as rosy in Renton's middle age as they may first appear. Daniel 'Spud' Murphy (Ewan Bremner) remains at once the tragic and comic clown junky trying and failing at rehab as his life and relationships seem to lie in tatters, his despair is palpable. He's blown the money Renton sent him. Franco Begbie (Robert Carlyle) hasn't moved on because he's been in prison for 15 years, and without parole seemingly faces no escape, making him an angry and dangerous caged psycho (he didn't need any encouragement for this as I recall!). Simon 'Sick Boy' Williamson (Johnny Lee Miller) has taken over his late aunt's pub the 'Port Sunshine' but that delivers meagre pickings (for his cocaine-fuelled lifestyle) so he runs a less than slick sideline in vice and exploitation with his Bulgarian girlfriend Veronika (Anjela Nedyalkova).

The narrative and cinematography are suffused with references to the loss of youth and thwarted ambition. Have our 'heroes' evolved? They aren't the same but, shaped by their various disappointments, there are plenty of pent up emotions and frustrations just waiting to burst out. Spud gives a voice to a recurring mantra, "First there was the opportunity; then there was the betrayal"; but this isn't as radical, angry or shocking a film as its younger sibling, which so captured and spoke to a generation just about to get off on 'Cool Britannia'

Screenwriter John Hodge loosely bases his script around Irvine Welch's original novel Trainspotting (1992) and its sequel Porno (2002), but gives us a fresh storyline around the various inter-relationships and a project to redevelop the pub/scam the grant/open a brothel; what could go wrong! Boyle cleverly cuts in elements of the original 1996 film, to evoke the wistful look over the shoulder from middle age.

T2's sound track includes a new rendition by the Prodigy of Iggy Pop's now iconic, 'Lust for Life'. Not perhaps the new soundtrack for the generation next to follow, but an effective underpinning of the pace and energy of this tale.

The relationships between the protagonists, the ties that bind, remain strong even if some of them are vengeful and violent.

In a week which sees the remembrance of Scotland's national poet, Robbie Burns there is a more than a whiff of tartan tinged Proustian nostalgia, but not for madeleines dipped in tea. There are whispers about the opportunity of a 3rd movie, although if that happens I hope it won't be the cause of any betrayal!

This is a funny film with some great laugh out loud moments (Renton and Sick Boy's larks in a Loyalist club and Spud's foray to a boxing club); it's also a poignant film with references back to earlier tragic choices and events (Renton missing his mother's funeral and a memorial trip to Corrour, the remote Highland railway stop by Loch Ossian), and though tinged with sadness it is a worthy sequel to the original. I'm unsure if it can hope to have an impact on a younger audience, but it will be evocative for all the 40-somethings and beyond who were caught up by it in the first place.

Whatever your opinion of it, the heroin film of the 1990s will never be forgotten. So the makers of Trainspotting have taken on a lot in revisiting it after 20 years. Given the presence of much of the original cast and crew, T2, a title with a slight whiff of "hipster edge", could easily have descended into an uninspired re-tread of the first film. Thankfully, after an underwhelming first few seconds, it proves to be anything but.

Edinburgh, 2017. Spud (Ewen Bremner) is a pitiful shadow of his former sparky self, living with the tragic legacy of heroin addiction and contemplating suicide. Begbie (Robert Carlyle) is in prison and hatching a plan to escape. Sick Boy, or Simon as he now prefers to be known, still fancies himself as a wide boy about town but is eking out a miserable existence running his late aunt's once thriving pub in the Leith docks. And Renton? Renton (Ewan McGregor) is running on a treadmill in Amsterdam (that underwhelming, rather ad-like first few seconds) and preparing to visit home.

The original Trainspotting was a meandering, episodic, black tragi-comedy about taking drugs. T2 is a meandering, episodic, black tragi-comedy about not taking drugs, and not really being the better off for it. Apart from a bit of cocaine, the only real drug on display here is nostalgia. The characters are addicted to their past, and are constantly recalling it in a rose-tinted glow, which leads to the film's best line: "you're a tourist in your own youth", deadpans Sick Boy to a nonplussed Renton. One could argue that the reason they are so obsessed with their past is that their present has proved such a spectacular let down; a series of failed scams and evaporated dreams which is really no better than what they got up to in their 20s, except now they are a little older, a little fatter and a little bit less energetic.

Though loosely based on Porno - novelist Irvine Welsh's sequel to his earlier Trainspotting – T2's story parts company with the novel after the first fifteen minutes or so. As in the first film, screenwriter John Hodge takes the bits he likes, changes the story to give it more of an arc, and conveys the essence of the novel all the same. He also adapts bits of the first novel that didn't make it into the first film, which fans who were disappointed by the omissions in the original adaptation will be delighted to hear. Officially, this is 'based on Porno and Trainspotting by Irvine Welsh', which is why we finally get some of the characters back stories and an explanation of why the whole business is called 'Trainspotting' in the first place. And the novel itself is used as a framing device in a very clever way that is likely to surprise.

Much note will be taken of McGregor's fabulous delivery of the screenplay's golden nugget, an unexpected re-imagining of the iconic opening monologue from the first film. It could have been a gimmick, it could have been crass, it could have been wince-inducingly awful – but somehow it's brilliant. Every word hits just the right note, every sentiment hits home as we realise, not entirely comfortably, that much of this anti 21^st century diatribe is every bit as true as the equivalent rant was the first time around.

There are references to the original film which provide rueful laughs – check out the staring through the windscreen scene; there are contemporary bolt-on's which are entirely fitting – Snapchat and Bulgarian hookers; there is the tragic yearning for lost loves, friends and family; and there is the guileless optimism that this scan could be the one that works. In a troubled, muddled world that seems so much more complicated than the world in which the original film landed, the bittersweet yearnings of these characters doesn't only seem appropriate, but strangely comforting in a sad sort of way.

Together, the two Trainspotting films prove that something pretty special happened when three young filmmakers decided to pull a story out of the heart of the Edinburgh slums. The original occasionally felt like a slightly overrated flash in the pan; with the sequel to accompany it, it has become complete and the films have jointly secured their place in the ranks of great British cinema.