Well lets explore the idea that it could be different models Cellular vs Wifi only, Max memory, and how about available memory.
My background: Member on the board since Mar 24, 2010 (I confess not active much except during upgrades to see what other folks are seeing) , I ordered the Ipad 1 within minutes of it being available online, same with the Ipad 2. I've not upgraded since because frankly my Ipad 2 has worked great and I've been patiently waiting, for something in the new ones to get me excited enough that I will not regret spending the rather large amount of money.
Here is my config:
64Gig AT&T Cellular model
Memory Free: 22 Gig while Running OS 7.1.2
Memory Free: around 16 Gig Running OS 8.0
Note: The Memory Free number is not exact comparisons because I did not look right before I upgraded It is the number now after the down grade, recall uninstalling/deleting some stuff to make room for the upgrade and the OS 8.0 number is what I recall when I looked at some point, it was likely not much less than that since I did not reinstall anything.
My comments about the slowness of the interface was while there was no apps open, but arguably there are apps I use that share my location always running...not sure how much of an impact that would have in slowing the device down but that and amount of free memory are certainly contributing factors to consider.. Anyone else that has made comments that everything runs the same or better want to post their configs for comparison? Of folks with same results (slowness) want to post theirs?