As a consumer:
1. You can not choose a new default application to handle various actions. Don't want Apple maps? Tough sh#t, when you click a map link that's what you're getting. Don't want built-in mail? Tough crap.
2. You have no choice but to use that bloated, awful iTunes application.
3. You can't view the entire file system on your iOS device (you can with Android)
4. You want an iPhone in phablet size? Tough. You want a water-proof smart phone? Tough. You can have this year's model or last year's model.
5. You get to overpay for that Apple logo; hope you like it.

More later, but for now...

#1, not entirely true

#2...at first I didn't like iTunes. It took some getting used to, but I personally like it now.

#3...generally but not entirely true, will talk about that later. There's a workaround I've been using.