Err...how could DS2 possibly be worse? They have more time to improve the engine, polish gameplay, they can reuse and recycle assets, etc. etc. The story could be worse, in theory, but the story is not really important to this franchise
It would be utterly shocking and ridiculous if the game was worse than DS1. The question really is:
Will DS2 be ENOUGH of an improvement over DS1:
To please the fans?
To bring in newcomers who didn't like demon soul and dark soul enough?
To get a 90% meteoritic rating?
To sell X% more than previous games, where X is a good enough number for you?