As a long time fan of the books, I am satisfied with what we've been seeing.
There are so many reviews and people saying "The movies were better".
Ah yes, the ones with Percy as a generic 'oh my god I'm the hero!?' boy with no personality outside 'shock and awe', Annabeth somehow feeling like a child of Ares more than a child of Athena, I don't remember a SINGLE good idea from her in the movies, and Grover being turned into the biggest black stereotype I had seen at the time.
My only small issue is the acting being a little stilted at times, but as they have more time to get comfortable with their roles the better it'll get, I've re-watched harry potter, and its always such a shock seeing how bad their acting was in the first movie.
Overall, I'm loving the casting, I'm really enjoying the choices being made for the series, and everything feels really good to watch.