I used iPhones exclusively from 2008 until a month ago, when I got a Note 2. I've never been this happy with a phone, ever.
For me it comes down to sacrificing a bit of coherence and reliability for a UI that you can streamline to your personal taste, and quite superior functionality (for the things I want to do with my phone, at least). Sometimes Android does annoy me, for instance it happens that some widgets I install start to contradict the system settings here and there, and sometimes I miss a more coherent design. But these are minor grievances for what I get instead.
My Note 2 is the first phone I've been able to use to write, format and send professional Word documents (using OfficeSuite Pro) without finalizing them on a computer first. Typing is warp speed fast with any of the swiping-style keyboards (I use the stock Samsung one), I can almost reach full physical computer keyboard speeds and I am not exagerrating.
Gaming is actually...real gaming on this thing. The iPhone is just too small. I bought quite a lot of games for my iPhones over the years but often grew tired of them fast because they felt so limited. Now I'm playing games all the time, and enjoying the hell out of it.
But my fave thing is my own personal UI. I can have my notes (Google Keep) immediately accessible next to an overview of my calendar on one homescreen, just a slick open surface with wallpaper + clock/date + swipe-able dock for 15 most used apps + a set of small, unobtrusive and good looking widgets for tilt lock, mute sound, flashlight, wifi hotspot and airplane mode on the middle homescreen, and a direct access music widget on my right homescreen.
I also use gestures for screen off, notification menu down without reaching for the top, double tap for app drawer (which can be awesomely organized with categories), two fingers swipe up for S Note, etc. And each app icon on the dock has a secondary function if you swipe up from it, like going directly to my GF in the address book if I swipe up from the phone icon. (All this thanks to Nova Launcher Prime).
All in all this makes for an utterly slick interface and I generally feel like my interaction with the UI is literally twice as fast and intuitive as it was on iOS. It's fun to use this thing. And then there's of course the back button - which feels like a total revolution when you're coming from iOS. I love it to death. Same with the ever-present settings menu button which works the same in most apps.
So yeah...I can wholeheartedly recommend giving Android a shot. The thing is that you can't get any real impression of how it works until you actually get your own Android phone and start setting it up like you want it to be. I fondled the Note 2 for months in the store and just wouldn't dare make the leap (I'm not made of money ) but after a day of owning it my picture changed completely.
I'm pretty sure I will get the note 3. I have mentioned in a previous post that it was the first phone that changed the way I used a cell phone. I actually never once pulled out a laptop or ipad while owning one. Also, the split screen is really useful when you are trying to copy something from a screen or have to jot down a quick note in the middle of a phone call.
..oh and lets not forget you cannot kill the battery in a day if you try