The reveal of Black/White Kyurem was done spectacularly. The game made use of the DS' visuals brilliantly here.
As for the gameplay, it's almost the same as the gameplay in Black and White, which is not a bad thing in the slightest since those contributions to the series were excellently done. And at the same time almost everything bad about the first Black and White were improved with these two games.
My favorite new feature was probably the Black Tower/White Treehollow. It was basically the Battle Tower with levels, EXP, and prize money, plus you got a free shiny dragon out of it.
I liked that it had its own final boss, too, Benga wasn't too bad. And in addition to that the evil team actually did something catastrophic and there wasn't a clear-cut happy ending.
Easily the most underrated feature.
There are so many items here. It's a great resource for a lot of items, including rare stones, thanks to the Black Tower/White Treehollow.
Almost all of the available Pokémon appeared in the game, with very few of the monsters being left out, and most of those were starters or legends. Speaking of legends, this game has 'em in spades. Heatran, the Regis, and Lati@s are just a few examples.
I don't care what you say, Ghetsis was gonna kill the player. Even if he only wanted to freeze you, that would have killed you, just a bit more slowly. The rest of the game is smooth sailing from there on out, I guess. The champion reveal is done well, though I feel it could have been someone else, as there was already a Dragon-type leader in the region.
The end credits theme is possibly my favorite in the series to date.
I will probably see Black 2 & White 2 as the perfect Pokémon games until they inevitably top themselves.