My dad once said to me, "You give a lot of books three stars." I do.
If I took any notes on the last three books of the Heroes of Olympus, I lost them along the way. This is probably an inflated review. I kept thinking, I'll know how I really feel about The Mark of Athena after I finish the series which probably means it was a typical middle book. It set up some stuff, but in the long run left me with loose ends more than anything.