I'd agree w/ knightofdragon and say that B2W2 are good games to get.
I have White (1) and both Black 2 & White 2, and honestly the game play in B2W2 is so much better, if only because when your repel wears off, it gives you the option to continue using them, instead of having to go into your bag to select it every time.
Additionally, there's some cool stuff like the shiny Dratini (W2)/ Gible (B2) and shiny Haxorus that you can get post game. The PWT just off Driftveil is pretty cool as well, and since I like it much better than the Battle Subway, so for me I find that items like Life Orb and Focus Sash etc. are much easier to obtain.
The gyms are shuffled around, and now there are new gym leaders: Cheren, Roxie, Drayden (who you only fought in Black1) and Marlon, plus a new Champion, though the E4 is pretty much the same.
As for Team Plasma, new clothing design and new boss - you still face Ghetsis and bump into N though, and you can battle N once a season post game.
And the best thing for me about B2W2... Zorua. I was so disappointed that Zoroark was only obtainable in BW by the possession of some obscure event Pokemon. As to how you get Zorua, I won't ruin it for you in case you didn't know already.