Oh, boy, that was fun! And funny! This is like the UK's answer to Harry Dresden - if Harry was way more mellow and his dog was a slipper with ears. Harry's dog might be named Mouse, but he ain't tiny. :) Toby still has it where it counts though.
Survey says: Harry kicks ass; Peter is swell bloke.
The world-building was pretty well-developed throughout the story, not just for the magic stuff but for London itself for us non-Londoners who don't know how London works. I imagine it's told in a politely backhanded enough way to still be amusing to those who live there though. We're told only what we need to know when we need to know it, and aren't info-dumped for no reason, yet it still manages to set things up for later books.
The case was interesting and certainly unexpected.(show spoiler)
Leslie looks like she's getting set up to be the Murphy of this universe, only much more mellow and less awesome. Though she could still end up being awesome later. We'll see.
I'm not sure at all why the American publisher changed the name of the book from Rivers of London - since the rivers actually are pretty important - to Midnight Riot. Sure, there's a riot and it happens at night, but it's not even the climax of the book. Com'n. Did they really think we'd need the promise of a riot to get us interested? That's horrible. This isn't like trying to get kids interested in a bunch of old guys sitting around discussing the meaning of life to a bunch of rocks (BORING!) versus wizards doing cool magical stuff with stones (AWESOME!). There was just no reason to change the title, and maybe it's just me, but it also introduces an unfortunate (most likely completely unintentional) racial implication. Peter's mixed-race. There's a riot. Must be connected, yeah? Let's make it the title! Boo! Bad job, American publisher! Bad job!
The narrator, Kobna Holdbrook-Smith, did an okay job. He has a nice voice, all silky and rich and mmmmm...wait, what was he saying? ;) I did tend to get caught up in the sound of his voice and miss the actual words he was saying, having to go back and re-listen and mmmmm... :D The downside is that he really needs to learn how to breathe properly when he's narrating. Lots of deep inhales at pretty much every stopping or pausing point. Comma? Time to breathe. End of sentence? Time to breathe. I did listen to the sample for the next book, and he seems to have improved on this point, so I'll continue with the audios.