I can see both sides of this. While Joe User might expect "Hey, we're slowing you're phone down because you're battery can't handle it" to be flashed in their face, I can also see Apple's perspective as a software developer. You shouldn't realistically be expected to tell the user every little thing you are doing in your software to help improve the stability of your product. 99% of the time, crashing / unexpected shutdowns always lose out to performance, period. What if the slow down still allows you to finish typing that email or message you were in the middle of writing? Wouldn't that be better than just unexpectedly shutting down while you were in the middle of it, making you lose everything you had just done? I know which I would pick as a user...