Gameslice's Geoffrey Keighley has voiced his opinion on the new Doom game. Overall he seems to be pretty mixed on the issue. Here's a snippet:
In twenty years when I think of Doom I want to remember downloading the 1993 shareware version – I don't want to have the pellucid brilliance of that moment tarnished or clouded by a "restored" version of the game that was released a decade later. Even if the new Doom is an absolute masterpiece, it will still inevitably be compared to its prequel.
I think the general thread in most people's opinions is "if it's great, then cool, but if it's not so great, it'll just tarnish Doom's legacy, so be careful, id."