Let me make one thing clear first - as good a game as Aberrant storyteller is, the system is in fact far stronger in its retrofit to D20, bass-ackwards as this sounds. The D20 version is actually more dynamic, more internally-balancing, and is a lot more accessible than the storyteller version.
Exception: The Taint rules are clunky. Not horribly so, but clunky. Not difficult to fix, but needing fixing.
Settingwise, nothing is changed from storyteller. Literally, the huge setting section at the beginning of the book is pure reprint. I have always been a fan of the reversal of the X-Men motif, where the societal hell of being a demigod is being a media icon.
If you like Aberrant storyteller and like D20, this is the product for you. Also: the Nova powers rules are OGC, if you look at the declaration in front (at least in my version). The really dynamic powers system alone goes far towards being worth the cost to purchase.