I wouldn't say its not that it cannot be used. And I wouldn't say that it is OS issues. It would be more on the apps support side. The problem is android has a lot of devices to optimize compared to apple products. Its a headache for app developers to create an app that works for thousand of devices. If you are a programmer then you will feel the pain.
Overall android has a Ferrari or a Lamborghini engine. But it just won't move properly. Unlike iOS it has a Toyota altis engine but it moves from point A to B smoothly.
And in all I still feel that android phone experience is still way better than iOS. But for tablet, and apps optimizations the iPad should still stay as a number one priority.
I know im going to get flamed for this.
I do agree on what you say about the apps part, however, the experience is still crap. For IOS, things just "work". Very minimal funny apps hang, sluggish, sudden crash, reboot syndrom.
Plus most apps work well with each other. For Android, some apps just do not get along. Also Android apps seem more like separate modules as compared to ios apps which feels more united. And don't get me started on the crappy Android eco system.
And the user experience nuances. Android just don't cut it.
Nexus 7 is supposed to be the flagship Android device, but to me it is very dissappointing.
Give me a toyota altis that can bring me to wherever I want than a ferarri that always breaks down.