One organisation which was tracking social media platforms said that in the first few hours there were 6,049,506 mentions of iOS 7 on social media platforms immediately after launch.
Synthesio said that some 827,189 of users complained about difficulties around installing and using the software.
Users claim that the new features and menus are a complete move away from previous versions of Apple's operating system.
Now users are hitting Twitter, forums and blogs asking for help as to how they can use the new Control and Notification Centres, force close apps, block callers, find popular apps and customise Siri.
The majority of these conversations were about the time it took to download iOS 7, error messages and an inability to download iOS 7 and asking for help from other users.
Today thousands of Australians are set to take to social media to voice frustrations as they try to upgrade. Owners of iPads are being told to delete content before the new iOS can be downloaded.
Hundreds of Apple product owners have called the new design cheap, dated or too much like other systems.
Aside from the software's overhauled design, its biggest change is the introduction of the Control Centre, and updates to the Notification Centre from iOS 6.
The new quick access Notification Centre shows new mail, missed calls and other notifications, plus a Today view that gives an at-a-glance look at the day ahead.
It shows live weather and traffic information, for example, updated in real-time as well as birthdays or upcoming events.
To open the menu, swipe down from the top of the screen and click the Today, All or Missed tabs to see the various notifications. The menu can also now be opened while the screen is locked.
The Today tab can additionally be customised by going to Settings, Notification Centre and scrolling to the Today View section. Views, including calendars, stocks and reminders, can be added or removed.
The Daily Mail said that the most significant security update on iOS 7 is the new Activation Lock feature.
Previous handsets let you remotely find, lock, wipe or send texts to a phone if it was stolen. The Activation Lock now means these can't be disabled without a user's Apple ID and password
Alternatively, the new Control Centre can be opened by swiping from the bottom of the screen and lets the user quickly access the Wi-Fi and network mode settings, change the screen's brightness and play or stop music.
This menu looks similar to the Notification Menu on the latest versions of Android Jelly Bean.
Along the top of the menu is Flight Mode, Wireless, Bluetooth, Do Not Disturb and Screen Rotation Lock. Below this is a slider that controls the screen's Brightness levels.
When music is playing, the section underneath shows the song duration, track and artist details, skip and play buttons as well as a volume controls.
It's also now possible to open the new built-in torch, clock, calculator and camera from the Control Centre, too.
The good news is that disgruntled iOS 7 users can downgrade to iOS 6.
Network operators are reporting weaker than expected demand for the colourful iPhone 5C, the lower-priced model Apple investors hoped would be a mass market hit.
Apple CEO Tim Cook said Apple was competing for a different part of the market.
He said: 'There's a segment of the market that really wants a product that does a lot for them, and I want to compete like crazy for those customers.'