I had a bit of a love-hate relationship with this book. There were times near the beginning where everything was very slow and I thought I might just give up. Towards the middle I kept expecting it to end, although by this point I was much more interested and didn't really want it to end, there was just something about parts of the middle which felt like the end was coming, even though I knew I'd only read around about half the book. Towards the end I wanted to do nothing but read it. I started a new paperback but only read a few pages because I wanted to read this one. I had to force myself to stop when reading on my lunch break so I wouldn't be late back to work. 
 I can't really tell you what happened towards the middle which made it more interesting. Technically there was really no more plot, and the plot didn't drastically change, I think maybe I just began to feel more about the characters, and that made me anticipate things which I saw as being inevitable- which in itself made me want to find out what would happen next. I wasn't always 100% correct in my assumptions however which stopped the novel from becoming predictable. 
 There was a point in the middle where I became rather confused actually, and a point at the end, but to say more would only serve to spoil. 
 Certainly an atmosphere of Victorian London is built up very well, you can almost see it, smell it, touch it, taste it. In terms of showing a place, and building at atmosphere it's got to be one of the best novels I've read. Don't go expecting something sanitized, everything is described in great detail. 
 My main problem actually is that the ending felt rather abrupt, which really doesn't seem to fit for a novel which is almost 1000 pages long, surely a few extra pages would be no problem?