I found it a little unlikely sometimes that the protagonist, Cecil, managed to run away to London and not end up addicted/abused/beaten. Maybe there are some rose-tinted glasses on what homelessness can really be like. Even the hardcore tramps are painted in a sympathetic way (and the London cab drivers). Skip diving is also a lot less pleasant than portrayed, plus store employees tend to get the really good stuff before it reaches the skips.
I'm not 100% but I think Cecil's art - remixing a famous actors work into new scenes - is fair use, it's certainly transnformative, but mash-ups usually tend to become copyright violation targets. Although, Cecil does download and use pirate apps I guess. I mean, he's not the average pirate - downloading a film/app because its free and convenient. A sympathetic pirate figure.
That said, it's a damn good story, had me up reading at 1am for 'one more chapter'. If you're interested in copyright and DRM then this is a good read and not too taxing. Also a very cynical (and accurate) summary of the UK parliamentary system.