The annoying part is the minority of apps that don't even work on other ARM phones running Android.
Sure thing, the hardware market is very fragmented which means not even a Nexus is 100% compatible with the ecosystem. Of course, whatever new iPhone Apple launches this year will have also have compatibility problems with old apps, and might never properly run 100% of iOS apps either.
This is the exact same thing we dealt with in the Windows ecosystem for years, but now its a huge deal for some reason. Heck, some old Gingerbread-era app works better on my modern phone than any Windows 98 application works on my Windows 7 PC. We have made progress.
One of the reasons I left Android is because some big apps written by big companies wouldn't even necessarily run properly if the phone wasn't a Samsung Galaxy xyz or a Nexus.
Sometimes big company apps are the worst! They want their iOS and Android app to look the same, and they develop it first in iOS, so the only solution is to bolt that iOS app UI onto Android despite how crappy it runs. Some of my most hated apps are from big companies, while some of my best apps (like are holo from head to toe) are made by small single developers.
But that isn't unique to Android. One of the biggest pieces of crap ever is one of the most popular Windows applications of all time- Quickbooks. The bad guy wins sometimes in real life.
The trick is: can it do the functions you need?
If what you need is responsiveness and consistent UIs, Android will never be for you.
If what you need is THE most functional mobile OS (as in can do the most computer functions) then welcome to Androidland.
Most people don't need that functionality and only buy Android thanks to marketing. Gotta love the sheeple driving down hardware costs for us nerds....