Who manages resources, decides and handles app suspension, instructs apps to free up memory "if and when it is needed"? Who does this if it is "not a task for the OS"? Especially when you claim that the user does not have to take care of the environment beeing filled up with garbage. But it does not seem that the OS knows better than me, which apps I am using and which ones I just open to look something up, it will simply close the oldest one if it runs out of resources. This can be really annoying and happens all too often if you are heavily using the device, even on the 1520 with 2 GB. Showing the OS which apps are not needed anymore just helps it to close the right ones.
I agree on the 1-N back statement, although it depends on the app. However, a convenient method to close an app is missing, when you still got the convenient method to keep the app open pressing the home key, which I also use where needed. The false statement from another guy about the shortened time to bring up task view made me hope, but I could of course imagine better ways than using the back button. Just have a look at tablet mode on the PC. I really have no problem to learn something new, but it should make sense. Current behavior on mobile just looks messed up.
In a team?
I did not even start it. Seriously, with the exception of the start screen on the 820 just hanging after boot, I do not understand all the complaints about loading/resuming screens, also from earlier W10M builds, how does it come to your mind?

And I was always happy with performance and battery life, do not even need a battery pack for a heavy day of geocaching! I am not complaining about anything else than a step back in usability.