iOS 7 is Apple’s biggest visual design change since Apple first released the operating system in 2007. Despite initial reservations from users to the colorful, flat update, iOS 7 has been adopted at a faster rate than any previous update to Apple’s portable devices. Still, there are significant issues with iOS 7, some simply side effects of a recent software launch, others intrinsic to Jony Ive’s design itself. Nielsen Norman Group (NNG) has written an extensive “user-experience appraisal” of iOS 7, highlighting each and every minute detail that makes iOS 7 more engaging, as well as the features and changes that make for unpleasant, frustrating experiences.

NNG covers the biggest revision first: the flat design. The lack of skeuomorphism might be easier on the eyes, but it makes usability much more challenging. Buttons that used to stand out now blend in with the background. Links that used to be very visible on the screen are now more easily mistaken for plain text. Even the iOS picker (scrolling dropdown menu to pick from multiple options, such as date or time) has become more difficult to navigate. NNG also believes that Apple has not given app developers clear guidelines in order to maximize ease-of-use for end users, and it shows.

The next category, swipe ambiguity, is one that plagues all touchscreen devices, but its implementation in iOS 7 is especially egregious. Three of the four edges on an iOS 7 device can be swiped to either open a menu or complete an action depending on what the user is doing.

Although NNG understands the obvious benefits of having an easily accessible Control Center, the act of swiping up, from any part of the screen, is one that iPhone and iPad users have been performing for years in order to see more content. Now, without careful placement of the fingers, scrolling on Safari can be constantly interrupted by the Control Center — though iOS 7 can be configured so that Control Center is not available while apps are open.

Spotlight Search and Notifications cause similar problems from the top edge of the screen. Even the seemingly innocuous “back button” feature of swiping from the left edge of the screen in Safari can interfere with basic website interaction.

There is no question that NNG sees major flaws in iOS 7, enough to warrant the claim that “Apple has demolished millions of hours of user learning by changing the icons.” The research group has seen improvements as well though, such as unlimited folder space, background updates, cleaner browser design and a polished settings menu. The group’s conclusion is still grim, however: Apple needs to reevaluate the user experience on iOS 7.