Three names you're likely to hear a lot around discussion of Paul Cornell's London Falling: Ben Aaronovitch. Mike Carey. And Doctor Who. And I think this is just; the first two write noir series about magic in London with certain kinds of legal involvement (though not really the same kinds) as this book does/is, and the third is what Paul Cornell has been doing with much of the rest of his time. Which I think you can totally tell. The beats fall in all the same places as a Doctor Who episode--when Matt Smith (or whichever Doctor it is this time) would be telling people to run, that's just when they need to run in this book also. It is not a very Whovian book in most regards, and yet there are a few pieces of aesthetic, a few influences of form, that come through the much darker thing to say, "Ah, yes; this man learned from Who."
The beginning was a bit slow for me. I had a hard time sorting out which character went with which characteristic tag, in part because the major characters mostly had British surnames, and the beginning was much more plot-heavy than character-heavy. Usually the thing to say is that a book began slow but that one liked it once it got going, but here it was the opposite: it began fast and plotty, but I liked it when I got a chance to settle in with the characters and really have a sense of who they were. Which did happen, and which I expect will be less of an issue in future books (and oh yes, this totally set up for future books).
One thing I really liked is that football--the soccer kind of football--ended up being actually important, important in its particulars, for a book about Londoners. You don't have to be a football fan to enjoy London Falling, and in fact I'm not, but I liked that it was not merely a side note or a decoration, but rather crucial.
Ben Aaronovitch and Mike Carey are hard company to keep, and I actually did like both of them better (Aaronovitch on the lighter side, Carey for wooooooez), but that doesn't mean that Cornell can't stand with them. I'll be interested to see where he takes this.