Apple iOS 8 is finally here, and the Internet is bursting with reviews and reactions, in particular with the news that a bug prevented the launch of the HealthKit app on release date.

"We're working quickly to have the bug fixed in a software update and have HealthKit apps available by the end of the month," a company spokesperson said in an email on Wednesday.

"The MyFitnessPal app, which supports integration with Apple's HealthKit, was temporarily removed from the Apple Store this morning to address some minor issues," MyFitnessPal said in a statement emailed to Reuters.

TIME has also reported that iOS 8 doesn't seem to be working well with iPhone 4S, even if the model is included in the list of compatible units for the OS update.

Experts believe that the latest operating system is optimized for the newer iPhones, iPhone 5 and up.

Other tech pundits, however, feel that iOS 8 is good:

"There is no doubt iOS 8 is packed full of really handy features, and other than the obligatory warning regarding first-release software, I can sincerely recommend upgrading to iOS 8," Michael deAgonia of Computer World wrote.

Mashable's Christina Warren thinks that the update is one of the best releases ever:

"The same is true for iOS 8. On the outside, it looks almost identical to iOS 7, but once under the hood, you realize there's something more powerful and useful at your fingertips," she commented.

Mark Rogowsky of Forbes offered a list of the great things about iOS 8:

"Apple has added the kind of features power users have been clamoring for but regular people will find incredibly useful while simultaneously refining a bunch of small things. The result is that iOS 8 is much more than meets the eye."

Just as with past updates, to update to iOS 8, visit Settings > General > Software Update.

If the phrase "Download Now" is not appearing, chances are you have to delete or transfer a number of files to have a decent storage available for download to proceed.

If you have a limited data plan it is recommended to download the update via Wi-Fi connection instead.