The system is based on dice steps. As your character levels, the action dice size increases. It is not d6 based, it uses everything.
The original hardcover had quite a bit of eratta, there was only one print run, and so only the softcovers got the benefit of updating. I never gelled with the races of Barsaive, but the system is very inspiring both mechanically and for setting.
I STILL use analogues to Parlainth in my games. Well worth stealing that from Barsaive. And hard to find the Parlainth boxed set these days for a reasonable price..wish I had never sold that.
"D&D was meant to be a free-wheeling game, only loosely bound by the parameters of the rules." Tim Kask, Foreword, Eldritch Wizardry 1976
"Maybe I'm just getting too old to want to have to deal with a heap o' rules and the steaming heap o' rules lawyers who go with them."-Gary Gygax
"...why have us do any more of your imagining for you?" OD&D- Afterward-Volume III