I've read
Titus Alone, yes, and... liked it but didn't love it, whereas the first two books are, as you say, an example of how great literature can be but so rarely is.
As you probably know, the story of Mervyn Peake's later years is an extremely sad one. The general opinion seems to be that he wrote the third book while in the early stages of the dementia that would later claim his life. Reading the book, this seems all too likely, to me. It comes across (to my eyes) as confused and dreamlike, like somebody wanting to tell you something but not knowing where to start. I enjoyed the book and will definitely read it again, but it doesn't feel like part three of that
wonderful story (really, no adjectives are sufficient to describe the brilliance of the Gormenghast series!).
I would be very interested to hear your views on it, Kurben! Do you enjoy it as much as the other two, and does it feel like a natural continuation of the story? Have you read any of the other less well-known Gormenghast books,
Boy in Darkness and
Titus Awakes? Personally, I haven't, but will surely get around to them one day.
Also, Wikipedia informs me that the Australian Broadcasting Corporation produced a radio adaptation of
Titus Groan,
Gormenghast and
Titus Alone in the 1980s, which was actually the first time that
Titus Alone had been performed on the radio. This sounds wonderful, and I would love to hear it.