Amazon pitched Fire OS 4 quite some time ago, and reports claimed the update would roll out the same day as iOS 8. That was back in September, but my two Kindle Fire HDX tablets didn't get the new OS until a few days ago.
I had given up checking on the OS update weeks ago, and it was an email from Amazon that informed me the update was rolling out. I was surprised to see that it had indeed been applied to both my Kindle Fire HDXs, and that it was Fire OS version 4.1.1. Amazon skipped version 4.0 and went straight to 4.1.1 on my tablets that had shipped earlier this year with OS 3.x.
The new Fire OS is not a major upgrade but a solid one. The new features promised by Amazon in Fire OS 4.1.1 are nice ones, notably the category Household Profiles which allows groups to easily share a Kindle Fire HDX.
The inclusion of the WPS office suite (see above) and better VPN support in the new OS are welcome for those bringing a Kindle tablet to work. The OS now has a backup and restore feature that saves all device settings, email and wireless settings, and bookmarks to the cloud. This makes it easy to recreate the desired user environment when moving to a new Fire device.
After using Fire OS 4.1.1 for a few days I am impressed with the improvement over the previous version. The system is noticeably faster, and graphics are smoother, particularly scrolling in apps. The subtle changes to the UI are nicely done and make using the Kindle Fire HDX even more enjoyable.
The Email app received a total makeover and now looks like the competition's offerings. The incorporation of the material design used in Android Lollipop is unmistakable, and the use of swipes to work with mail is similar to both Android and iOS.
The onscreen keyboard has gotten a welcome facelift as control keys are a different shade than the rest. The result is a keyboard that is easier to use at a glance.
Fire OS 4.1.1 uses a full-screen mode on many integrated apps that displays more info at a time. App controls pop up in a translucent mode that is similar to iOS. Working with these apps is more productive than in previous versions.
Amazon claims that battery life is extended with Fire OS 4.1.1 but it hasn't been out long enough to verify. It was already pretty good under OS 3 so that would be icing on the cake. There is a new Smart Suspend feature in OS 4.1.1 to stretch battery life even further. When turned on, this prevents the system from polling the network continuously when sleeping. It will still poll for updates for email and the like, just not very often.
I should emphasize how much faster the system feels overall. There are no lags, no delays, and even third-party apps that haven't been optimized run fast and smoothly.
Having just experienced the iOS 8 update on both the iPad and iPhone, it's natural to compare the Fire OS update to Apple's. I find the Fire OS update to be a more significant improvement overall than the iOS upgrade. This is a result of the UI improvements, better performance, and the added value of the office suite now included.
Note: Just before publication my ZDNet colleague Adrian Kingsley-Hughes told me he'd just received another update, version 4.5.1. He's in the UK which may have something to do with this new version.
According to Kingsley-Hughes, the 4.5.1 update introduced a bug in the Email app, so perhaps it's a good thing that not many have received it.