I am most likely in the minority here, but I really enjoyed the Royal Knight's line. I felt that it had many s..good sets, and was the last of the decent castle sets before the dark times... before the Fright Knight's....
Much of this however could be clouded due to nostalgia. I was a mere 6th grader with the release of the Royal Knight's line, and thus have memories with such sets as the Skeleton Surprise and Royal Knight's Castle. I will concede that earlier sets I owned in childhood were sometimes superior (Forestmen sets come to mind) but I do feel that the Royal Knight's had quite a bit to offer. In my mind, the decline of castle started with the Fright Knight's, and not with the Dragon Masters as others here would claim. That however is my opinion.
Now, to the purpose of this thread, a review of the King's Carriage. I think that this set is enjoyable overall. You could get a king without buying the Royal Knight's castle (the "set" which only included the king and horse should not have been released due to this set in my mind), you got a decent amount of soldiers to protect said king, as well as some treasure, armaments, horses, and useful pieces.
The overall design of the set is not awful, but could have been improved apon. A brown or mostly black carriage would have been more visually appealing in my eyes. However, the entire Royal Knight's theme seems to have been black on blue, so I cannot fault Lego for being consistant. The main fault with this carriage is the fact that the interior holds only the king. I would have prefered a larger interior so that at least one more minifigure could have ridden inside with the king, such as a queen (which should have been released in this line).
All in all however I think this is a good set. You can buy several of them and modify the carts to create merchant carts, farmer carts, or infantry carts without much difficulty. 8 out of 10.
"A chair like this is like a girlfriend! Why would you trade in an old one that's comfortable for a new one that could be a pain in the butt?" -Archie Bunker-