Since I got my iPhone 5s (after 3 years of iPhone 4), I am happy I can finally take pictures without worrying about getting a greenish blob in the center of the picture (with indoor lighting especially). Also, the iOS7 camera app is greatly improved.
There is one detail, though, that I don't consider as a real improvement: the burst mode. Why? Because if you hold your finger on the shutter button, it automatically triggers the burst mode and you can find yourself quickly with tens of useless pictures if you just wanted to do a single capture.
The awesome "capture upon release" trick
Before iOS7 and burst mode, holding your finger on the shutter button did nothing: that was the point actually. Because the picture was taken "upon release". It doesn't seem like a big issue to most people, and it's arguably not a huge problem to people who have always taken pictures by simply tapping the on-screen shutter button.
However, holding your finger (typically your right thumb) on the screen means you hold your phone tighter, and with better stability than if you keep that finger in the air ready to tap. Before iOS7, you could just hold like this, wait for your subject to be ready or simply your framing to be the way you like, and then release your thumb to take the picture without making the screen shake. Before iOS7, I could dispense this arcane knowledge to random people with the assurance of earning their eternal gratefulness.
Now of course, things are different. People should avoid holding their thumb on the shutter button...at least with the Apple's Camera app.
That's when third party apps enter into play. Most of them still function like the pre-iOS7 Camera app used to.
I haven't tested them all but there is one I stick to generally for its simplicity of use mixed with deep controls: Camera+ for iPhone by tap tap tap.
It is a great app and while I do use the Apple Camera app for the amazing slow motion 720p and Full HD 1080p video modes (and maybe someday for the burst mode, when I find a use for it), I am happy to have Camera+ for single pictures.
I bought Camera+ soon after getting my iPhone 4, and recently I bought their 2 optional sets of filters (there are already many free filters included) because I thought I owed it to the developers. They have been updating the app regularly for years now, and keep refining it without sacrificing performance or simplicity of use.