I had originally decided I was not going to upgrade. I had my original iPad 1 for 2 years until the iPad 3 came out, then kind of played musical iPads.......I switched from the iPad 3 to the iPad mini but couldn't deal with the non Retina display. Switched back to the iPad 3, but then a few months later the iPad Air came out. I loved my Air because it gave me the full sized, beautiful Retina display but it didn't weigh a ton like my iPad 3. I had intended on sticking with the iPad Air for at least 2 years after going back and forth, but I got $351 trade from Best Buy so I took the plunge. So at the end of the day, I paid $287.49 after tax and brought home a 64 GB iPad Air 2. Was it worth it? For that price, yes it was. I absolutely LOVE the fact that it has Touch ID. And going from a 32 GB to a 64 GB was a nice bump as well. All in all do I think it is a major difference from the iPad Air that I traded for it? No, not really. Don't get me wrong it is a wonderful device, and if I still had an iPad 4 or less it would be a no brainer to upgrade to the iPad Air 2. But I can honestly say that if it wasn't for the fact that I got $351 towards the trade in, I would not have traded up just yet.
As for the case question........I've never been a fan of cases for iPads. It makes sense for certain usage scenarios (IE: in schools with kids using them). Since my days of having an iPad 3 I have always just gone with a smart cover to protect the front and no case. On the iPad Air that I just traded in, you'd have been very hard pressed to find so much as a nick on the back of it, and that is with throwing it in and out of my laptop bag every day and sliding it across my nightstand every night when I go to bed. The metal they use is rather sturdy, so I say just go with the Smart Cover.