Let me open up by saying - Pure awesomeness in design, build, features and user friendliness. It is a damn expensive piece of gear to buy and I had to alter my lifestyle to buy it, but it is all worth it. Don’t go in for an Apple device, if bare essential and "need" is your buying motivation.
Go for it if you need something special, a pleasure of use, a pack of features, a choice of over 500, 000 apps and the sheer thought of the fact that this is the most superior phone on the planet today and is the choice even for Billionaires...
The greats - Design, interface, ease of use, apps, right size, lifestyle
The not so greats - one day battery backup (any good smartphone will not run more than a day though), expensive, expensive, expensive.
Thats it there are no other bads. I wont get into specs details, you will obviously read all that at the Apple site. Weighing against an Android (samsung types), better interface, higher build quality, more apps and the "Open source" cr@p is a defence line for Android users and they dont even know what to do with "open source"
Lastly - An android phone is just a compromise for Apple.