Unfortunately, it's only slightly better than the old multitasking model. Let me cite MR's article (
https://www.macrumors.com/2013/06/1...ements-multitasking-support-airdrop-and-more/ ):
"Multitasking and Background Downloads - Apple's new multitasking APIs are designed to allow apps to update and download content in the background at intelligently scheduled times. For example, a Twitter app might incorporate this functionality, downloading new content in the background while the phone is not otherwise in use, staying up to date without unnecessarily draining battery. Push notifications can also initiate content downloads. "
That is, you can in no way except any app to run in the background and, say, continue outputting video to an external TV. Something Backgrounder / Quasar / Background Manager are all capable of as one of the best usages of these tweaks. It's just a somewhat more advanced download support - nothing else. Definitely not the same thing as in Android / Symbian / Windows Mobile or even Windows RT's "snap" mode.