So far I think White 2 is the best Pokemon game I've played. It's only slightly better than the last one, but there were loads of small things I didn't like about that (the linear map, the music, the story, the only-new Pokemon initially).
So far all that has been fixed in White 2. The story is similar to Gold/Silver, it's basically a "explore the world!" plot but with eventual enemies that aren't too sinister. I've only played for 4 hours and I'm taking my time, but I've already got my 2nd badge.
Approach it like the 3rd version (Yellow, Crystal, Emerald, Platinum), but this time there are two "3rd versions". It's definitely aimed at regulars to the series so maybe that's why it feels quicker?