I have heard of some few people who really didn't like the new look, and I recently found out that Apple has not signed the old iOS 6 to allow you to "downgrade" if you already upgraded to 7. However, mostly, the reaction from people that I have seen and talked to is overwhelmingly positive.
There are some new features that utilize the hardware (and thus drain the battery) more, that I feel most people probably don't want. So, if you are one of those who upgraded, only to find your battery draining faster, hopefully this will help you out.
1. Per-App Use of Cellular Data
Definitely, go through the Privacy section of the Settings app, and turn off Cellular Data access to the apps you don't care if they use cellular or not. For example, all those apps that show ads, you don't need to consume your cellular data plan for that.
2. Multitasking and Background App Refresh
iOS 7 has greater support for background app execution, which of course means more battery chewed up. Predictive use based on history means iOS 7 will determine, based on how you use your apps, whether it will allocate background processing to running apps. For example, if you read your news on the NPR app each morning during breakfast, then before breakfast time if the NPR app is running in the background, it will "wake up" and download the latest news, instantly ready for you during breakfast. Double-tap your home button and swipe up to "throw out" the running apps you are no longer using.
3. Location Services
Location Services is Apple's way of making GPS location available to the Apps. Of course, in order to read the GPS satellites, it has to turn on the antenna and this takes up battery. There are various aspects of Location Services you can control, such as for what functions you want to make it available. Some new features that take advantage of this are:
- Location-Based iAds. When you see Apple iAd advertising banners in apps, it now can target based on your location. Translation: Apple makes more money from advertisers wishing to target their ads, but using up your battery to do so.
- Popular Near Me. In the App Store, you can now find out apps that are popularly purchased in locations near where you are. This might be cool, say if you are traveling, don't want to talk to anyone, and just simply find out what people around you buy. Me, I say who cares.