As someone who loves the original Percy Jackson series and Heroes of Olympus, this was a fun but very low-stakes addition—it's more like a spin-off series than a 6th book of Percy Jackson and the Olympians, which is how it was classed. I enjoyed it, but set your expectations more like you might for the stand-alone "extra content" books than you would for a main series book, because there's nothing too groundbreaking here.