Actually I did the reverse. I went to an iPhone 5 from my Galaxy S 3.
I had the original iPhone 2G, 3G, 3GS, and 4. I switched to Android when the 4S came out, so I've used Android for around 1 1/2 years or so. I've had many different Android phones, but liked the GS3 the best. But I eventually got bored with Android in a few regards.
Basically the one thing that makes people switch to android is the main thing that got me to switch back to iOS. All the customizing. I just got bored with spending too much time altering and tweaking my android phones. I did the custom rom thing, made my own debloated roms, tweaked all parts of the roms I could. It was a never ending battle.
I was always OCD which was running in memory, did I properly close an app when I was finished, always checking to see what is running in memory....etc...android to me was just too much maintenance. I was spending more time tweaking the OS and always keeping tabs on what was running, that I found that I wasn't spending enough time just enjoying the phone.
Another thing I could care less about is all the talk about multitasking on android, which I really never did. When I was done with a program I was done, no need to keep it running in the background. After all it's a smartphone and not my desktop computer. Why would I want to do all the same stuff I do on my computer on my phone?
Widgets are cool yes, but I only ever used one. That was the weather channel widget, which now I just have the weather on the drop down window on iOS.
I just think iOS is more smooth. On my GS3 I replaced the SMS program, the Keyboard, the email client....etc...on iOS, everything just works great and I don't feel the need to want to replace anything on it. I don't have to tweak anything, the majority of programs stop when I exit them. I can easily double tap the home button and just clear out my recent program list. It is just like they say..."It just works".
Now I will probably get flamed for the above, but the point I am trying to make is regardless of what OS you are currently using, you will get bored with it and want to switch to something else, until you get sick of that and want another change. The grass isn't always greener on the other side.
I like the Note 2, and was debating on whether to return my iPhone 5 and get it instead. My main issue with the iPhone 5 is that I find is very difficult to get used to the small 4 inch screen after using the 4.8 inch screen of the GS3. I guess that is why the Note 2 is so alluring to me with it's 5.5 inch screen, and my eyes aren't getting any better as I get older. But although I love the big screen of the Note 2, I just don't think I want to go back to Android at this point in time. iOS is actually refreshing for me to go back to.