I grew up on these books, and it's one of the only series that I read regularly even after all these years. My hopes for the show were small considering how many changes I saw from the trailer, but after watching the whole show, I can say that I was even more disappointed.
I understand that they have to change *some* things for a show adaptation, but it truly felt like it was the Annabeth Chase show through the first half, and that they gave away the plot for the second half. Annabeth, Percy and Grover were 3 steps ahead of everything and everyone the whole show, which ruined the element of surprise that the books had. The show drastically changed the heart of the characters, and I didn't really feel the friendship build like it does in the books.
Not worth watching, better off reading the books again or finding a different series to attach to.