I read Pawn of Prophecy and I'm starting Queen of Sorcery. I really love the world Eddings created. It's too bad a good setting book was never published. A well-done rpg aimed specifically at the Belgariad would be amazing, as well.
Things I like:
Belgarath and Polgara. Just well-done NPC's, without being overbearing.
The Grolim. Kind of like Nazgul, but not really. I think they are cool.
Silk. He's just cool. In fact, the whole fantasy spy subtext to the series is really fun.
The Secret Language. I confess, I've had some kind of variant on this in every game I've run ever since I read the Belgariad back in the 80's.
The Bear Cult. Also really cool. I wonder if it influenced how Malar's religion was portrayed in the Forgotten Realms sets.