I'm trying really hard to give it a chance. I'll start with the positives. As a whole, the series is staying pretty accurate to the book's plot, which is a huge improvement from the movies. I like that we're getting vital scenes that were left out in the films (and that the episodes are titled like the chapters--love it!).
I'll be honest in admitting that the casting is really bugging me. I grew up reading these books. I grew up with these characters. I fell in love with them and wanted to meet them and was inspired by them. And when you grow up with book characters and are given a certain description of what they look and act like, that's what you expect. I wanted a black-haired, green-eyed Percy. I wanted a blonde-haired, gray-eyed Annabeth. I wanted a blonde haired, blue-eyed Luke. I wanted the characters to look and act like how the books described them. So I'll be honest in admitting that I was pretty disappointed by the casting.
However, I will say that they are growing on me as the show continues. From what I've seen of Luke, his actor embodies his character very well. Percy needs a bit more fire and fight, but I like his one-liners. Annabeth is still the most off for me. I don't think it's the actress' fault--just the way they've written the script so far. There needs to be more scenes where we're able to see her intellect and strategic mind shine through because THAT IS ANNABETH. That's what I always respected and loved about her. I'm hopeful that as the show continues, we'll see more of that side of her.
Overall, I'd say the show is worth watching. Do I feel a little let down as a longtime fan of the books? Sure. But it is still EONS more accurate than the movies, and for that I am grateful!