Most people I know have one, and are not looking at updating ever until it breaks. For browsing/email/facebook, you don't need the latest one. Even the iPad 2 is enough to do those tasks. I feel there's much less urgency to update than on the iPhones and the Mac.
I would've agreed with this except that my parents, who only do exactly that, decided to buy a new one because they said the old one was starting to feel slow. It's exactly as fast as it is the day I gave it to them for that kind of stuff but they went to the Apple Store to get my dad's phone serviced and they played around with one of the demo units. My dad commented on how much faster it felt and BAM, they walked away with a new iPad and a replacement iPhone (out of warranty but cheaper than a new one).
My ipad 2 is certainly much slower tan it used to be. I believe the reason is the new iOS versions. Even switching between apps feels annoying.
Apps are also written / optimized for much newer hardware.
Yep, should never have updated it past iOS 6.
The 120 Hz screen refresh on the latest iPad is a game changer. It has surprised me how noticeable to non-techies it has been when I let them play with it.
They don't know why they like the feel and they use different words to express it, but it's real.
Not to mention iOS multitasking not available on older iPads.