I'm reading this series, PERCY JACKSON AND THE OLYMPIANS, with my son who picked up the first one and devoured it in a day. The first book in the series by RICK RIORDAN, THE LIGHTNING THIEF, was a fun romp. It's hard not to compare it to HARRY POTTER since it's young adult fantasy and borrows a lot of the patented Rowling formula. For instance, the kids in the story are all "special" (half-mortal children of the ancient Greek gods) who discover that they are special as young adults struggling in a tediously "normal" world. They are sent to a camp where they divide up into houses, one for each of the gods, and compete for house pride.
Since Riordan has begged the comparison, then, here it is. This book isn't as good as the first Potter book. Characterization is shallow, lots of details are hand-waived, and the plot, though interesting, is fairly transparent and rushed.
Despite these negatives, I enjoyed the book and am looking forward to the second book in the series.