Vanilluxe is also nothing to laugh at in terms of stats, having a 530 BST that is on par with Lapras, making it one of the best BSTs among Ice-types.
The thing, though, is that Vanilluxe's movepool is nonexistent. Ice Beam, Flash Cannon... Signal Beam, I suppose (although I like my moves to be at least 80 power if their main purpose is to do damage)... Lapras has way more moves/better coverage.
Anyway, to chip in my 2 cents, besides the aforementioned designs (which I personally don't mind so much), my chief complaint is that the encounter rate is ridiculous in B/W (I think it's better in B2/W2). It's like, you take three steps, and you encounter a Pokemon.
The other thing I'm not fond of is, again, only a problem in B/W: the regional dex being so small. Unlike with other games that have ~150 Pokemon to choose from, the Gym Leaders/Elite Four stick to being monotype (for better or for worse), but team building is still meh at times.
There is one thing I really like about B/W, though, and that's how they save the climatic confrontation for the end of the game. It makes so much more sense to have the big showdown against the villainous team happen at the end of the game rather than before the 8th gym, since their plots are typically more "take over the world" things nowadays. Cuz "Hooray, you saved the world, now go get that 8th gym badge" results in a bit of a drop of... buildup, or whatever.
Also, if it means anything, B2/W2 are my personal favorites in the Pokemon series.