I've only read the first novel, The Savage Caves.
That said, I enjoyed it quite a bit. I think the Iconics were a great move on WotC's part, since it gives us a cast we can become familiar with as the game progresses. However, an obvious flaw in that was that they had no personalities.
These books fix that. We finally get a real idea of what the characters are like, and it's great to see. They finally become more than just a collection of numbers and stats, the way good characters should.