What can I say? Dorothy Dunnett was an amazing writer - her characters are complex yet utterly believable and (almost) wholly sympathetic (the good ones, at least), her plots are intricately planned and keep turning unexpected corners, and her style of writing leads you through all this without losing a single thread of idea, character or narrative. I love these books because they require you to think in order to understand what's going on and all the subtleties of the situation and all the references to previous occasions or to character traits.
These books are also what got me interested in geography - a huge number of locations are described within, and the writing makes you want to visit them all, to visualise the book's events happening where you are standing.
Worth reading if you have any interest in historical fiction, or love complex plots and many many characters (there's a character list at the front - the one in Book 8 is 16 sides long), but DO START WITH THE FIRST BOOK - they won't make nearly as much sense otherwise.
If you find Niccolo Rising or any of the other Niccolo books difficult to read (and I did at first), try reading the Lymond Chronicles first - the plots are almost as complicated, but the characterizations, while no less believable or complex, are sometimes less ambiguous. The Lymond books generally move faster, plotwise, and are easier going and a bit more romantic (in the idealistic sense of the word, not the love sense).
Please, please, do at least try and read these books, don't dismiss them, they're really excellently written in every way. There's a good reason why Dorothy Dunnett had a diehard following of fans during her lifetime, fans from all different backgrounds and locations.