It looks like the gang's all here and accounted for! The fact that they're still alive suggests that they've cleaned up their acts somewhat, so it looks like we'll be exploring some new territory with them. They've at least moved on to less fatal drug habits by the looks of things.
Begbie's getting out of jail though, and he doesn't strike me as the type to forgive and forget. There seems to be some sort of heist or high stakes marijuana deal at the core of the new plot, so if Begbie is putting differences aside to get rich, it's doubtful he'll make the same mistake again. My guess is he'll probably try to fuck over our intrepid narrator if he gets the chance, so Renton had better watch his back.
Sequels like this can be grating but there's a ton of interesting territory that can be explored here, and I'm genuinely interested in what these guys have been up to since the last time we saw them. It seems like Renton has really missed Spud and genuinely cares about him from what we see here.
There are a couple cringe worthy red flag moments here that could indicate the sequel is going to be a giant pile. Renton's updated rant about Twitter and Instagram doesn't ring true for me. I can't see a nihilist like him really giving a shit about selfie culture one way or another. Hopefully that's just a formality to let us know that we're in 2016 and the guys are still primarily concerned with just sitting around in pubs arguing about Iggy Pop and James Bond when they aren't running around being full-on psychopaths.