I have had all 3 OS's. Who ever says WP, Android or Apple is hard to use then you have no business owning a smartphone. Lest take a look at it as a phone first. They all have a icon with a phone in it, thats what you use to make calls. Press it, dial the number and send. Seems simple to me, right. Next you have a icon for messaging. It will have a picture of a cloud/bubble, what ever you want to call it. Press it and text something to someone, Also pretty simple to me. Next you have internet. Now WP is a pic of circle "E", android chrome is a circle with different colors, apple says safari. Now if you own a smartphone I am sure you know which icon will be the internet. Press it and the web opens. Type a address and it takes you to it. Once again pretty simple. Now these are your common features of a smartphone and what is mostly used, at least by me.
Now, lets take a look at the apps, which is why most, if not all people by a smartphone. No matter what OS you have , you will have a app store and I am sure it not had to find the icon for it. Now once you download a app, I am also sure that you know what the icon for that app looks like right, perfect. Open the newly downloaded app and use it. Kinda simple if you as me, on any OS so far. And I will say that this goes for all apps, mail, FB, Youtube, Twitter, etc. They are all apps, coming from the app store. They will have a pic for you to recognize it.
Next is the OS/Phone settings. Now this is where things become a little more difficult. Like I said I have owned all 3, so with that said this what I think. WP 8.0 on my 928 and Icon was pretty simple to find stuff. I have the M8 on 8.1 and the settings have become more difficult and has more user setting than before. Which is expected because 8.1 has more features. still none the less it becoming more difficult to find stuff. Apple was the 2nd easiest. My 4s and 5 had what seem to be the same settings. I would venture to say that its pretty close to WP 8.1 if not even as far as finding a specific setting. Android was the hardest for me. But its expected because it is so feature packed that there is a setting for everyone. I always had a hard time finding some setting. Found myself Google-ing it sometime. Now if you are just a no nonsense smartphone person that just want a smartphone for phone calls, text, couple of apps and a camera, then WP and Apple are for you. If you like all that and are always changing setting or trying some new feature out, etc, then I think Android is for you. Its not to say WP or Apple are lame or something is this department, but if you just set your phone once out of the box then they are easier by far than Android.
These is what I think of people who say one is easier to use than the other. Your ignorant or you should have a smartphone. Its a phone with icons. You press the icon and it opens up. How hard is that? Also if its not on you home page you scroll to the side till you find it. Pretty damm simple if you ask me.