I watched the first episode. As previously mentioned I haven't read the books (I think I probably would have they'd come out when I was slightly younger but I just spent my teenage years wanking) so I can't judge them on that level. I did think it was a bit lame that it started with onscreen text explaining "THIS IS A DIFFERENT WORLD..." and so on. Like, yeah, I think the viewer would have figured that out by themselves, thanks!
On the other hand I did feel slightly lost at times when they kept talking about "gyptians" (who I guess are like gypsies but on canals so I wasn't that confused) and such. Anyway it was a pretty good tv show. The world seemed interesting and the acting was good with some standouts. It didn't really reveal where the story is going yet though the "next time" bit at the end seemed like a recap of the whole series and gave too much away, possibly over-compensating for the first episode not having a big hook ending.
Ruth Wilson is a really magnetic screen presence and I'm sure she'll be delightfully evil. I always like James McAvoy too and hope he comes back from the north pole or wherever he is and does stuff.
I'll keep watching it.