I've been looking forward to Lord Sunday for a while, and it did not disappoint.
Arthur's been facing tough decisions since Mister Monday, and they get no easier here. The colorful world of the House is as confusing, dangerous, and beautiful as ever, and the the consequences of his decisions are felt in both the House and our world.
The only drawback is that it had been long enough between the books that it took me a little while to get back up to speed on who the different characters were. The end was also a tiny bit disappointing; I'm not sure why--it's not as if it came completely out of the blue.
Definitely worth reading, though I suggest reading the series together as one block, now that that is possible.