For the most part, I found it to be an exceptionally mature story. And when I say mature, I mean literally; not the connotations attached with "mature content". What I found refreshing for a mainstream Bollywood movie is that it lets the two protagonists be completely accountable for their actions. There are no random circumstantial twists, no confusing triangles or pentagrams or some other external forces in play. The notion of you can be as stupid as possible, mess things up as much as possible but that it you ought clean up the twisted little world that you built for yourself was brought out elegantly. Of course, the entire dual story with the flashback seemed like more traditional Bollywood stuff but I guess that was put in to probably help bridge the gap for people with orthodox expectations.
Another completely different aspect of the movie is that it was scattered with a lot of memes from my life. And when I say a lot, I mean a lot. Just to make it clear, I'll try and list a few: thinking everything will be ok as long as I'm playing some stupid game (on a PC or the likes of a gaming console), a very specific aerial shot over the Thames that seemed very close to a sighting I had when flying over London, mulling in front of the two towers: iron pillar & qutb minar (which happened to be my phone wallpaper for 2+ years), believing pursuing one's passion as profession is everything in life, hopping aimlessly on and off those cable cars, look at a bunch of people dance and struggle hard in attempts to fit in, using the expression "angreez ban raha hain" and then indulge in something similar at a later point, etc. etc. Of all the movies I've ever seen till date, this one had the maximum numbers of bits and pieces from my life strewn in a different sequence, in a different context but certainly in ways I could relate to.
All in all, watching the movie worked out for me but for anybody else, the maximum they can hope to derive of it is as earlier said: a Bollywood movie with a mature storyline.