Glimmerglass is another good faerie book with unique aspects and puzzling characters. It's also a successful beginning entry to a series: it has a complete story unto itself, but there is more than enough material left to expand upon in future novels. This aspect is one of the most crucial to me when reading a series, and I'm happy to say that Glimmerglass provides.
Glimmerglass is the tale of Dana, a high school student who is fed up with moving from town to town and having to deal with her alcoholic mother. She knows her dad lives in Avalon (the one place on earth where the faerie realm and the human realm intersect.) What she doesn't know is the reason her mother has kept her from Avalon and her father her whole life - she's about to find out that it's a lot more dangerous there than she ever imagined. Dana runs away to Avalon and soon learns that she's a Faeriewalker. While humans can't enter Faerie, and the Fae can't enter the mortal realm, a Faeriewalker can enter both. A Faeriewalker can bring magic into the human world, and technology into Faerie - this makes Dana very dangerous, and very desired by those who seek power. As Dana learns who she is, she must also decide who to trust - and it's not an easy decision.
I loved how difficult it was even for the reader to determine who could be trusted and who couldn't. You are forced into trying to make a judgement on very little information - just like Dana does, and it gives the reader a great perspective on what Dana is going through.
If I had one complaint it would be that is was unclear if all humans know about the Fae. Dana speaks of them as if they're no bigger a surprise than a English person, but it's not exactly clear if everyone knows of the Fae or if Dana simply does because of her heritage. It's not crucial to the story, but I was curious about this for the first portion of the book.