On the night of September 19th, early morning on September 20th, 2017, iPhone users in Vietnam were able to officially download and update to iOS 11. This is the latest operating system version from Apple with many more modern features and applications, and it's also the default operating system on iPhone X, iPhone 8, and iPhone 8 Plus – the newest models from Apple.
While iOS 11 may offer support for iPhone models from the 5S onward, the question remains: should you upgrade these older iPhone models to iOS 11?

Should you upgrade your iPhone to iOS 11?
iOS 11 has its downsides as well.
Designed primarily for the latest iPhone models like iPhone X and iPhone 8, iOS 11 appears to have apps that aren't fully compatible with older hardware, even iPhone 7 Plus or iPhone 7.
For more details, see if iOS 11 satisfies Apple fans.
Too heavy for iPhone 6 and iPhone 5S?
Many iOS 11 apps require 5GB of free space for installation. However, older iPhones, especially 16GB or 32GB models, likely have already used up a significant amount of space for other apps or software, necessitating either deletion or reliance on iCloud storage.
Even with apps removed, installing iOS 11 on iPhone 5S or iPhone 6 is not advisable as the devices may become sluggish and laggy when running apps with iOS 11. Numerous user tests have shown that installing iOS 11 makes their devices feel heavier and slower than ever before.
Watch additional video tests of iOS 11 installation on iPhone 6.
As a result, advice from many suggests that iOS 11 is primarily suitable for iPhone 8, iPhone X, and iPhone 7 or 7 Plus, but not recommended for iPhone 6S or earlier models.
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