A grand finale, spoilt only by the series' determination to make Steerpike an anti-hero rather than the villain of the books. Maybe they thought it would work better on screen.
Although, inevitably, huge chunks of the book were omitted, most of the key events were not only there, but were very faithful to the original. The murder of Barquentine; Flay, Titus, and Prunesquallor tracking Steerpike and catching him gloating over the dead twins; the subsequent death of Flay; the hunting of Steerpike (complete with his catapult!); Titus' final killing of Steerpike; Titus finally leaving Gormenghast (and riding past a boulder 'like the sail of a ship' -- a reference to the third book in the trilogy) -- all kept very close to the book. Only the scenes between Steerpike and Fuchsia were significantly different (in most cases those scenes never appeared in the book).
Well, it was never going to be as good as the books, but it was certainly a brave attempt, and probably came as close as anyone is likely to get. Most of the cast were wonderful, and captured (albeit sometimes in broad strokes rather than fine details) the original characters. The vision of the castle itself, while different to most people's expectations, was true to the books except in minor details. From the reactions that have appeared on this web-site's guest book and message board it seems that the series has managed to captivate even people who have never read the books -- no bad thing, and no bad achievement either -- and to satisfy most people who have read the books.
I have every intention of buying the video and watching the whole thing again (which has to be some sort of recommendation!). I am currently re-reading the books, and although I am trying to efface some of the images that have come from the series, I am quite happy to picture Gormenghast Castle itself as the castle of the series.
The nearest I have to a major complaint is that the character of Steerpike, although excellently performed by Jonathan Rhys Meyers, was substantially different from the Steerpike of the books -- the original character was far icier, far more subtle, and would never have committed the histrionics seen in the series.
Oh, all right, one final carping point: the castle appears to be built on top of an extremely high cliff -- how does it manage to flood so easily? (In the book the castle is surrounded by hills and mountains).