Hmmm... Is it just the darker scenes that lacked detail or is it also the brighter -- outdoor daylight -- scenes too? Maybe they applied some DNR to those darker scenes to remove some grain (as grain can become an issue in low lit scenes though one would've hoped that whatever's done would be in accordance w/ the filmmakers' wishes in this regard) and ended up softening the whole thing.
Judging from the High-Def Digest review, I'd be inclined to wonder if that's not the issue (though that review only suggested that it's likely an issue w/ the source and didn't go as far as to wonder if DNR was applied).
Still, it sounds like a worthwhile upgrade anyhow, especially w/ that $10 rebate.
_Man_