Yes, it was traditional "philosphers of mind" who found him dismissive, mainly because those are all basically Mysterians.

For instance, he cut Chalmers no slack on the incoherency of Philosophical Zombies.

The title promised more than it delivered, but nevertheless, Dennett's efforts in attempting to achieve that goal were a refreshing break from the incessant and fruitless bickering over whether the mind is a physical phenomenon.

That isn't the witty riposte that it is apparently thought to be. It really does "explain away" consciousness by reducing it to plausible physical processes. This reduction also applies to things like qualia, which is where nonmaterialists get upset as qualia (or equivalents) are also invoked by people like Nagel and Chalmers to argue against the physicality of consciousness.

The core argument from Nagel / Chalmers is that that there is a subjective element to consciousness which has no physical explanation. The reasoning for this is always an appeal to intuition. If you accept that there is "something that it is like" to see red, be a bat, etc, and that the "something that it is like" is above and beyond the physical processes of the brain -- the firing of neurons -- then you by definition cannot accept a purely physical explanation of consciousness. Dennett's book argues that this is mystical nonsense (or, charitably, wishful thinking) and the "something that it is like" is simply what happens when particular types of physical processes occur in the brain.

It's no surprise, therefore, that "explained away" is a criticism if you're a nonmaterialist. But if you're a materialist, then "explained away" is actually a good thing and the purpose of the book.