"Hello, I'm The Nostalgia Critic. I remember it, so you don't have to!"
1. The reviews are just plain hilarious. Many are unaware the great writing's courtesy of two people, Doug Walker (the NC himself) and his brother Rob Walker (the cameraman and occasional actor in the sketches on ThatGuyWithTheGlasses.com).
2. Recurring gags and animated characters bring an air of continuity. The gags include "A-CHUCK A- NORRIS!" and the Nostalgia Chick-originated "Big-Lipped Alligator Moment", while the animated characters include Casper, the Friendly Ghost ("TIMING!) and the Big Elephant in the Room (who will go away as long as you respectfully mention the late Johnathan Brandis).
3. To add to the above, a certain memorable line from a reviewed film will often make several appearances in other reviews. For example, a clip of Raul Julia's line "OF COURSE!" from Street Fighter is played every time a villain is seen plotting world domination. And of course, the classic argument-stopper, "I WAS FROZEN TODAY!"
4. A lot of the comments are made up of cultural resemblances, in-jokes, and behind-the-scenes trivia. For example, when he reviews The Star Wars Holiday Special he casually mentions that Carrie Fisher was doing drugs at the time, possibly to help us viewers get a handle on the special's perpetual weirdness (I don't think it works, though).
5. The many alter-egos of Doug and Rob Walker make appearances to help, nitpick, or pretty much belittle The Nostalgia Critic. These include Douchey McNitpick, who prompted the two "Top 11 Nostalgic F***ups", and the Hunter S. Thompson-esque Raoul Puke, a pioneer in "Fozzie Journalism". And of course, who could forget SANTA CHRIST!