Marleybone is by far my favorite world. Everything about Marleybone is cool:theme,opponents,music, and other factors. The only negative stuff are the rooftop combat zones and the difficult dungeons.
I like Marleybone too. The combat zones are no big deal IF you take your time and watch how the mobs move. I rarely get pulled in anymore, and if I do it's because I didn't take my time. The dungeons at the end are difficult and long but a real challenge. :)