I found the first movie to be better than I thought it would be (don't know the books), and the second one was a solid follow up but disappointing in a few ways.
I was very disappointed that Annabeth had so little to do because she was the most interesting character in the first one. Also, the new character Clarice was a carbon copy of Annabeth when she initially appeared.
I was also disappointed that the "Sea of Monsters" had literally ONE sea monster in it
I spent the whole movie looking forward to a bunch of fantastical creatures!