Hopefully iOS7 is as big a change as System 7 was for the Macintosh, otherwise the iPhone is about to enter a death spiral. Unless something major happens, I'm done with the iPhone when my contract is up. 3G, 3GS, 4 and 5 have progressively been both better and worse products to own. And other than it's weight, I think my wife's 4S is still the best iPhone Apple built. But without a major boost to the OS, there is nowhere to go.
Contacts: without parent and child filing system, contacts on iOS and MacOS will remain a nuisance to use.
Mail: somethings got to change because it's really a poor experience on the iPhone (iPad is much better, but there's more real estate).
icon only navigation: really cumbersome. we need a -shudder- start menu...
Siri: so spotty I forget to use it when it would be useful. And because it requires speech, can't use it in many places. Why can't we type a request into Siri?
calendar: customization is necessary. MacOS has it, iOS no. Can't even customize alarms, or have more than two.
notes: really poor and outdated. and the bug where if you are editing a note and don't hit done before a shared note updates and you lose the note forever has to be fixed. my wife and I have lost valuable information, never to return.
Safari: Apple should implement a forced "x-out" over all pages and ads, because it now seems that companies are serving ads that can't be closed and don't work with Safari to autoclose automagically. So the website you are trying to visit it permanently buried.
Prevent unauthorized opening of iStores by Ads: again, don't let ads take over your phone. because third party advertisers have no scruples.
It's up to Apple to continually improve the iPhone and prevent third parties from ruining the iPhone experience. Over the last 2 years, Apple has done little to further either mandate.