and I'm loving it already!
Topics that others explain incompletely, this book covers well the first time. Example: the indentation rule. LYAH, much as I love it, lets you know that indentation is important and what common practice is, but leaves you without a firm grasp on all the "what ifs." Real World Haskell lays it all out there the first time but without taking a lot of space to do it.
Having already worked my way completely through LYAH and "Write Yourself a Scheme", and written a few scripts in Haskell, I was a little tempted to skip or skim through the first few chapters of RWH. I'm glad I didn't; there's lots of great insights in that material.
So I've just reached the first chapter where they're really digging in to some "real-world" code: a simple JSON library. My biggest gripe so far has been that exercises have been a little scarce, and they come at the end of the end of a section, textbook-style. I prefer exercises integrated into the text: they strike while the iron is hot. See this lambda calculus introduction for an example.