Put simply, Gamefaqs is by far the best place to go looking for NES reviews. The site has a virtual monopoly on the game info universe, multiple thousands of readers can send in thier reviews of any game. Don't think that just because the reviews are fan-written, that they are bad, for the most part reviews are on par with your typical NES Retreat reviews, sans the imagery and fancy tables. Gamefaqs doesn't post reviews unless they are at least feasibly long and contain intelligent sentences. They have more quality than many of the NES-site reviews out there.
The best part, though, isn't the quality but the quantity of reviews on Gamefaqs.com. Say you are looking for a review of a particular game, you could go to any NES site and you have a hit and miss chance of finding the review there (miss, more likely than not, even sites with tons of reviews still have 40-50 at the most). At Gamefaqs, you almost know beforehand that a review will be there. The only exception is if the game is super unknown, and even then you have a substantial chance of finding a review.
There are people out there that have made a hobby of writing reviews for Gamefaqs, hundreds+, and you will see thier name quite frequently. It's easy to find a reviewer that you generally agree with and relate to. Games can have more than 20 reviews, so you get all those different opinions. Aside from all that, Gamefaqs covers every system imaginable, and not just NES
When it comes to game reviews, Gamefaqs is in a league of its own. When I want to find a specific review, I go straight to Gamefaqs. It is because of this site that an NES review database will never work. We already have one.