A lot of people have said that iPad 2 doesn’t seem appreciably faster than iPad 1.
Has anyone stopped to consider that it’s probably because the apps you’re using are still written for a single core device?
The same thing happened to computer users when dual core CPUs were released – sure, you could run more programs concurrently, but since each program only used a single core, until they, and the underlying operating system, were rewritten.
A more direct analogy might be the retina display on iPhone 4 – it took a while for apps to be rewritten to support it natively instead of just doubling their pixels.
I’m willing to bet that iPad 2 will go through a similar process – for the time being things will feel the same, or at least a little snappier (as mail, spotlight et al will use one core while your app uses the other).
As apps are rewritten to support multicore and iOS 5 is released (which will no doubt boast better multicore performance), iPad 2 should feel like it is speeding up.