Where do I start.... I'll just use development reasons.
1) You need a Mac to develop for it. (I'm talking officially, and not hackintoshes or whatever frankenmac people want to use.)
1a) Macs are stupidly expensive, if you want to develop for iOS, you'll need a wodge of cash just to buy the devices to develop and test on. In comparison, you can pick up an android device for £40 and everyone has a windows machine don't they?)
2) You need to pay the developer licence every year. Once for iOS, and once for Mac OS. (If you want to develop for Mac as well)
3) The iOS API is restrictive. (Have to keep updating your published apps with each incarnation of the iOS software.
4) Apples verification is quite difficult, and their feedback for rejected apps is final, opaque and non-negotiable. (I.E. Your app doesn't look 'apple' enough, rejected. You have a quit app button, rejected.)
These 4 reasons are enough for me to dislike it.