I love my iPads (including new Air), but I have to say, the lack of multiple user logins are my #1 complaint about iPads (iOS, but you usually have your own phone), and has been since they came out in 2010.
It's a huge PITA in my family because we have 2 iPads that my wife and I both use, but a lot of the time you have to grab the "wrong" one when you can't find "yours" or one of the batteries is dead or whatever, and then it won't have your email, or Safari bookmarks, or iMessages/FaceTime, it won't be logged into your Game Center account, etc.
I can't imagine how bad it would be if we had kids involved as well. There you might have even bigger issues, like if your kid accidentally deletes your work email, or whatever. And, if you want to use parental restrictions, that then means everyone who uses that iPad has to live with those restrictions, which is not fun.
Apple needs to get on this, it's bad enough they have dragged their feet so long, but now this is a real, significant point of differentiation for MS and Android (I don't know if multi-user logins are built into base Android, but I know some Samsung tablets have it).
Hopefully TouchID sensors in iPads will make this easy for them to implement, and easy for us to use, but I hope they are working hard on that so when the hardware is ready, the software will be too.