My full review is here on my personal website. I'll post a few excerpts here, though:

4.5 out of 5.0 stars

The very worst thing about this book is the “empathy link” between Grover and Percy. Yes, it’s useful and serves it’s purpose, but it seems a little too convenient. What exactly does it take to form an empathy link (I can’t quite remember if this is mentioned in the book) and why does he only share one with Grover?

The very best thing about this book is that a Polyphemus (a cyclops – one of Grover’s fears) wants to marry Grover! :-p Too freaking funny! Okay, that isn’t really the best part, but it is the funniest. Grover actually ends up being trapped because he’s tricked onto Polyphemus’s island while searching for Pan, the god of the wild. Luckily, this doesn’t interfere with Percy’s quest. :-D