I had plenty of problems answering phone calls on my iPhone -- it would be glitchy and unresponsive and I'd miss calls.
Even more annoying about the iPhone is the always growing "Other" space on the phone. I was constantly short on disk space with no way of knowing what the cause was or how to clean it up.
The bluetooth stack would crash every week disconnecting all my bluetooth devices temporarily. Very annoying when you have a smartwatch.
My wife's iPhone screen doesn't turn off after she uses Siri sometimes -- it'll just say on all night long.
The entire iPhone 6 (non-S) line was total garbage. Tons of people bought these and had nothing but problems.
My point isn't so much to rag on iPhones -- they're actually really solid devices -- and I highly recommend them to non-technical users pretty much exclusively. They are hands down better than the vast majority of Android devices.
But I switched from iPhone to Android on this last cycle and couldn't be happier -- this article covers much of what's good about it. But I love the flexibility and a lot of little touches that iOS devices don't have. And I think all devices have different problems. My Android phone is not glitch free either.