I don't use multitasking often. However when I use it, I use it to copy and paste things from one app to another or to a message I am writing. This is an essential feature I just need sometimes. Also, if you want to go back to the exact point in an app you have left, let's say after reading a message, it's more practical. If you go over the homescreen, man apps just restart, and that's how it should be.
The way notifications work on Windows Phone at the moment is not acceptable. I don't need a notification center, but I need a solution.
I explained this before, I'll explain it again. Let's say you use WhatsApp, Viber, Skype, and Facebook. Just four basic apps, nothing power-usery about it. Of course, next to this you have also an email account, missed calls and messages. That makes 7 notifications you can get. Now, how many notifications are supported by the Windows Phone lockscreen? Excactly, 5.
That means, if you want to know if you have missed a message or a call, you have to start your phone, enter the pass-code, and then scroll down to your apps every time. Of course, you can have all of them on top of your homescreen, but that negates the entire freedom of having a choice to personalize your homescreen.