Taken from Den of Geek.com
First things first: Discworld devotees will be delighted with how this TV adaptation has turned out. It's faithful to the plot, broadly speaking â some scenes are left out for narrative and time reasons, but that was to be expected â and the world of Ankh-Morpork, the mythical Wyrmberg and the rest of the Disc is spectacularly created on-screen thanks to some stellar special effects.
Casting is also pretty well handled. David Jason brings an unmistakable passion to the role, and Sean Astin â despite conceding to have little knowledge of the books before taking on the gawdy shirt of Twoflower â was obviously enjoying himself. Christopher Lee was the voice of death â sadly not matched by the cheap-looking special effects â and we were told, beforehand, to watch out for The Patrician: a superb cameo by the legendary Jeremy Irons, whose voice dripped off the screen.
Here is the rest of the review for The colour of Magic: