Generally if I start a book I will finish it (unless it is dire) but often I take a while to return to it.
Suzannah Clarke: Jonathon Strange and Mr. Norrell - I found the conversational and gentlemanly narration very difficult to stay with, the general lack of economy of words and the length of time it takes the author to say anything is frustrating. Although I did like the treatment of magic and have been told the book is very weighted for action towards the end. I am about 35% through and this is in my almost non existent "to be finished" pile. I found this a shame as it came recommended from another forum I frequent.
I got half way through this, and enjoyed it, but just couldn't carry on for some reason. Just too lengthy, I think.