That's not to say that Thud isn't a good book. All the usual Pratchett qualities are there: a decent plot; page-turning prose; familiar characters; and a threat to Ankh-Morpork that only grizzly Commander Vimes can put down in a no-nonsense, old-fashioned, common sense way. It's funny, exciting and intriguing. But there's the nagging feeling that this is a bit too familiar. You know how this is going to turn out.
I'd recommend this to anyone - as long as they've had a nice long break between Pratchetts.