This was my first Irvine Welsh novel, and I think it's fine to read this series a bit out of order. I'd seen the film before and loved it so was excited to pick up the book, knowing most of the time the book is better and loses something when adapted to film. In this case however I think Danny Boyle, and John Hodge (screenplay writer) did an incredible job and improved on the original. The book is still great, and the characters brilliantly written, but it has a few drawbacks for me personally.
 
The switching of POV between chapters is something I tend to enjoy in books, with one condition, it's always clear who's POV you're reading from. In Trainspotting this is not the case immediately, after a few sentences or maybe a paragraph or two it tends to be clear, but it's hard to be immersed the whole time when at the start of each chapter you're unable to picture the scene as you don't know the character involved.  After a while you can pick up on nuances of the style between the characters inner monologue but since it's all written with a phonetic Edinburgh accent it took me a while to spot. One additional point there is that although for me this style of phonetic spelling was fine and I enjoyed, I can imagine if you've not lived in the region or heard a lot of the accent before it could be a problem. Obviously in a film the POV issue is resolved just by not having to picture the scene at all.
 
The book also has much less of a narrative, it's much more a collection of short scenes in the lives of these characters. The film adaptation re-orders some of this and creates an arc following Renton from being to end on a kind of anti-hero redemption arc which just doesn't really exist in the book but is hinted at.
 
I still enjoyed the book, but it wasn't quite what I expected from the film. I'll read more Irvine Welsh in the future and I’m sure I’ll enjoy it more going into it knowing what to expect.