My initial read through of this system made me think "custom AD&D". While it does offer some interesting new mechanics and revisions of core character classes, I found the layout of the document daunting and a bit wordy. About halfway through the essential mechanics my curiosity left me.
There is an extensive list of character classes and powers that are uniquely specific and yet not too complex. These are well done.
I think there is a lot of potential here for a solid game, but I'm the type of player who likes extremes. Give me WoTC-rules-lawyer-delight or total freedom. Challengers seems like a good middle ground, but I'm not partial to that style. Overall, I'd say this is a good read, but I think I'd need a more reader friendly version if I was going to try and use the system.
[3 of 5 Stars!]