RE4, aside from the Leon and Ada string, had basically nothing to do with the series. And I say that as someone who thinks it's one of the best games to ever release.
What is resident evil now? That's hard to even describe lately, the franchise itself just changes too much. From OT impressions the entire game of 6 actually has slower and more atmospheric moments and has a massive variety of enemies that are pretty damn horrific and well designed.
RE6 has moments like the end game of RE4 too sprinkled throughout the chapters, there is a lot of great atmosphere throughout. Prerelease media is mostly showing explosions and stuff, but it's always trying to appeal to the mass market. RE4 also was not scary at all, though I never thought the series in general was.
And the pure combat of RE6 is a lot of fun. Mercenaries lives and dies on that sole factor, and 6 gives you much more to work with than ever before.