I don't know what happened to the cover of this one. The prior two books had great covers (if not very story-accurate). Then suddenly this one. I like either the US or the UK covers of the first two, but not this strange amalgam.
More substantively, this book is basically a continuation of the prior two, and not, for once, the climax of a trilogy. In fact, it's not really a series at all. The whole story is essentially one long novel broken into four books. City of Dragons picks up where Dragon Haven left off. The dragons et al. have finally found Kelsingra - sort of. There's a complication that takes most of this (slimmer - despite the listing, mine was about 350pp) book to solve. I didn't find that to be very credible, basically. They've trudged through miles of swamp, through danger and disaster, and survived it all. But now they can't conquer what is really a pretty feeble obstacle. I had trouble suspending disbelief, since it's not credible within the story world itself, and it reads mostly like a convenient device to delay satisfaction. Maybe Hobb felt three books of trudging would be too much.
The writing is almost up to the Hobb standard. Almost, because in this book (and to some extent in Dragon Haven), there are signs of sloppy editing. For example, there are several places where a line of description is repeated almost verbatim in succeeding paragraphs - a pretty clear sign that the tidying up didn't get finished. It felt like watching one of those TV programs (e.g., Castle) where they're so keen to ensure you got what's happening that they keep telling you. Over and over. Granted, it didn't happen a lot, but it made me feel someone was asleep at the screen. To some extent, that's true of the series so far. It's well written, and I read the books eagerly, but it's just not as intriguing or intricate as prior trilogies in this world have been. Nor are the relationships as engaging; there's nothing like the ambiguity of the Fool here. The closest thing is the wonder about whether dragons will turn out to be likable, or just majestic.
The book does finally include some news about Tintaglia, but nothing that really convinced me that it made sense for her to have been missing for so long.
All in all, a good book, and from someone else, I might give it a 3.5. Here, I'll drop to 3 to note that the series is really a bit below Hobb's standard, and not what I'd hoped for in a story revealing some of the secrets of dragons and Elderlings.