I had the S3 and returned it to get my iPhone back, I know I know, it just lagged A LOT. Idk why either because I wanted to like it so much, all the YouTube videos I watched, the S3's UI was smooth as butter, but the AT&T one I had was very slow at opening and closing anything from apps to settings to the Internet. It just really bugged me and I was within the first 30 days so I swapped it out free of charge. I'm not done with android at all though. I'm with iPhone for now just until I figure out what I'm gonna do come Xmas time. I may get the S3 again after it gets Jellybean, My friend has the nexus with JB and it is so smooth and quick. My girl has the HTC ONE X and it's amazing, but it's horrible at multitasking , no biggie tho the phone is awesome. So ya def good choice getting the HTC. I jailbreak my iPhone as well and I'm very curious to see how similar "rooting" is to jail breaking for when I get another android phone
There is a difference. I have never owned an iphone, but both my roommates have one that are jailbroken. I have messed with there phones and noticed some similar things, and some very different things
First off with iphone... You cannot leave the "apple" community, for example... the iphone developer will take everything given to him/her from the original apple source. and they will continue to build upon it (themeing) but I dont even think you can change your kernel, governor, or clock speeds on a iphone.
Android is a mini Linux computer that has the full capability to almost run anything (based upon your hardware capability) but here is where is it is similar... most android developers will take the SDK from google and start themeing (easiest on the nexus products - google) but here is where it gets complicated. Since there are so many android phones.... each company has there own systems (overlay) running on top of the original android source. therefore limiting the development process for each phone.
Android can literally run iOS (with some minor tweaks) if apple was an open source.
Plus apple made somethings easy with the themeing app (I forget the name) and can easily be applied. But if I want to run Jellybean on my Android phone (especially an HTC phone) will involve some complicated steps. Involving Fastboot, a boot.img, the .zip file, an unlooked bootloader for full rooting capability (from HTC), making a nandroid backup, and wipeing the phone clean. Its a lot more complicated. But complication = more things you can do. Especially if you know how to write codes and scripts.
With enough research, you could turn your android phone into whatever you want.
But Apple has one advantage.... with one phone, one operating system, same button, and same source. Making it 10 times easier.
Hope that helped a little,
(PS. Im not a developer, nor a pro, just an avide flasher - so don't shoot me if I said something wrong)