It's very hard to give it a good description without giving too much away, and I really do need to read it again because I don't remember it well, but I loved the series. I think it was 10 years ago that I read it.
It takes place in a world where each person has an animal familiar that is bonded to them. The familiar is basically a part of them. The main character is a 12 year old girl. I believe you find out very early on that she actually lives in Great Britain, but she lives on a world that's a parallel universe to ours.
Towards the beginning of the first book Lyra hears of children and their familiars disappearing, including someone she knows of.
Her uncle is a fancy important aristocrat and he thinks he has discovered that parallel universes exist. There's some interesting religious stuff in it. I would say it's kind of fantasy kind of sci fi.
Yeah, they really did not do well with the 2007 movie. Hopefully a different approach, and the 8-part TV format, will suit the material better. I really enjoyed the series, it was one of my favorites as a teen.