Let's put it this way - I don't think there's a single character who appears in each of the ten books, though a few come close. There are three main continents, each of them with a few of the ten novels focused there, and for the most part with their own cast of characters, though some do travel between the continents. And even so, even within any single book, the cast of characters is already very large and you'll find yourself regularly referring to the provided list of characters at the front. Add to that huge amounts of back-story, a bewildering variety of races, religions and magic systems, and it does all become a little overwhelming.
All of that does make for a very epic, grand feel, but at times too much so - there are just too many demi-gods, actual gods or simply immortal humanoids walking around, and not every clash between them can be as memorable as it really should be. And while the cast does have dozens of well-written, memorable characters, it also has dozens if not hundreds more who are less unique.
Don't get me wrong, I liked the series and really loved parts of it, as I said, but it's certainly not for everyone.