This is that I mean up here - the complain about iOS not being customisable; yet they don't bother going all that deep on their own devices any way.
What you're missing and probably many iPhone users is what customization means. It can mean anything from the type of background you use to the type of ROM you're running.
For example, one way in which EVERY Android user customizes their experience, which you probably wouldn't notice, are the apps and widgets available on their home screen. In iOS you just have every single app and you can organize it by folders. In Android you have an app locker which contains all of your apps and only those that you use most often can be on your home screen.
We can use the same phone and the same app and our home screens may LOOK similar to the unsuspected eye, but the utility we get out of our platform will be custom tailored to us.
For example, let's take the ever so commonly used weather apps. On iOS you have a million different options, just as you do in Android. However, in Android I can put a widget on my desktop which will display the info that I want to see at all times and it may be different than the info that you want to see. For example, I just care about the current temperature where I'm located and at my house. My friend on the other hand doesn't care about such things, but has a radar that he looks at all times.
Here's a screenshot of widget choices for one random app as an example:
Here's one with a radar:
Let's say you and I are both big-time YouTube freaks... in iOS you have a YouTube icon which will take you to the app, but in Android we can put a widget on our desktop (the same one, mind you), except yours will show you information important to you and mine will do the same for me.
Customization is a a vague term as it doesn't define
what you can customize. On Android the answer is "everything." What do YOU want custom?