BBC/HBO did a TV adaptation of the full series, aptly called "His Dark Materials". I didn't enjoy it quite as much as I did the books, but it was a good adaptation (and much better than The Golden Compass).

The books won a bunch of awards and were very well received when they released. The first one, Northern Lights (The Golden Compass in the US) came out in 1995 so it was fairly popular for a few years as the "premier" young adult novel, but it ended up being dwarfed in popularity by Harry Potter once that released (as did, well, everything else on the planet).

I think the books were a little less popular and well-received in America. In part because Philip Pullman is a British author, so obviously he got more attention here in the UK. But also, quite a few Christian groups - particularly in America because, let's be honest, most evangelical Christian groups are American - took issue with His Dark Materials' world and themes. It doesn't paint the church in a good light at all, and the series' God analogue, The Authority, is pretty tyrannical. Although, funnily enough, a former Archbishop of Canterbury, Rowan Williams, was one of the biggest supporters of the series - he felt it basically highlighted the dangers of dogmatism and attacked the ways religion could be used to oppress rather than Christianity itself - so obviously not all Christians were offended by the series.

Anyway, yes! Not only is the world fantastic (and it only gets more interesting and wild as the series goes on) but it also handles the characters really well. The way it handles the main characters - children who age into teenagers throughout the series - developing feelings for each other and discovering sexuality was done in a really thoughtful and age-appropriate way (for the characters and the audience). It addresses some interesting philosophical concepts, too, including some religious ones - I'd say the spirit, the body and the soul is a pretty key theme throughout, albeit not necessarily in the same way Christianity approaches it

I'd start by reading the books - Northern Lights/The Golden Compass, The Subtle Knife and The Amber Spyglass - and then watch the TV series. He's also written other books in the world - some novellas, and (currently) two out of three books in a second trilogy called "The Book Of Dust".