From an OS perspective, Android itself has many issues. iOS is still more polished. You can argue about how it's a grid of icons or whatever, but iOS has a very cleaned up.
http://www.androidpolice.com/2012/09/18/ux-things-i-hate-about-android/
This article details JellyBean issues. I've noticed at least a couple like the Gtalk button that does nothing, different app icon sizes, contact photos looking like ass, inconsistent menu button location, etc.
4.2 has the vibration issue where in-app vibration is completely ignored. Gchat and Gmail all vibrate in vibrate mode now despite not doing so in 4.1 and obeying the in-app vibrate settings.
On top of that let's not talk about how everyday is a different beast. Sometimes apps remain open. Sometimes GPS continues to drain battery long after Maps has closed. Sometimes Facebook gets stuck syncing. You can blame the apps themselves, but there's also a part of the OS that isn't very good at battery management unless you spend the effort.
I understand iOS lacks features we have in Android. I can't backup my Temple Run progress easily. I can't have fancy widgets. I can't customize the hell out of my lock screen. These are inherent limitations in the OS itself, but it's not so much a lack of polish.
So yeah, it's inconsistency, bad design, etc that continues to plague Android. We've come a long way since 2.x, but Android 4.x was what Android should have been. It's like a fresh start like when Apple was at iOS 1. 6 years later it's a very polished OS, but Google still needs some time to clean up 4.x.