It's a blog! Mainly of book reviews.
On the blurb and in the Introduction, it's stated that the title story is about Titus Groan, though he is never named. Well, he's called "Titus" twice and the setting so closely resembles the Castle of the Groans that there is no doubt at all, as far as I can tell. It's a good, weird, story, too - worth the tiny second-hand price I paid on its own.
The other stories are varied in quality but never bad. The one about the mysterious dancing clothes is particularly good. I'd read a couple of them elsewhere but they turned out not to be the best ones, strangely.
If you are a fan of Peake, I strongly recommend this collection.