GameInformer made it seem as if there are major changes. (E.g. if you fail to complete an objective, the plot will twist around your failure, and come back to haunt you.) Since BL1 came out 3 years ago, I'm sure BL2 will have imroved graphics, animations, etc.
QFT.
During my time playing the game, I likely ignored 90% of the weapons that were dropped. In fact, on my Roland playthrough I think I only went through about 10-15 different guns that I actually stuck to until level scaling made them useless.
Also, finding the "secret" gun chests was more often a disappointment than not. More than half the time you'd have something better. And chances are that an enemy dropped that.
Either that, or a rocket launcher comes out when you need a SMG, or a pistol pops out when you only have skills with assault rifles... etc.