The one we are using got the update and after a rather fast 780 MB download we started to install the new Android and Sense.
HTC promises that Software update 4.16.401.10 contains important enhancements and bug fixes including Android 5.0 Lollipop update, Lock screen and Notification are getting new Lollipop UI style with enhanced privacy features. Recent apps now support multiple pages and the new User Interface includes additional search functions within settings. You can simply search for an option without needing to know where exactly to find that particular setting.
It takes almost 40 minutes to install the update, but that really depends on how much stuff you have - if your phone has hundreds of applications, that definitely slows things down and our sample is rather bloated. At first boot, it is hard to notice any difference between previous Android 4.4.4 and Sense 5.0. The new Android 5.0.1 with Sense 6.0 will bring slightly updated icons, the app drawer will look very similar to the previous one. The fonts and icons are smoother and nicer but there is no white background in the app drawer that we saw with some other Android 5.0 devices.
The update made the phone slightly faster. You can notice a performance increase from 42822 to 43962 in AnTuTu 5.6 benchmark.
In Geekbench 3 the phone scores 967 in the single-core test and 3013 with multi-core test and definitely outperforms the Samsung Galaxy S5, which scores 938 in single and 2836 in multi core test.
The biggest chance is the Android 5.0 user interface changes to the lock screen as well as the task manager. You see the new updates as tiles in the lock screen. This looks nicer as it is refresh from the previous notifications. The task manager gets Android style carousel flow, where you can easily find the running application and kill it, or launch it.
The only thing that we noticed and didn’t like it is that in Chrome browser application tabs are now part of the task manger flow. HTC Sense 6.0 treats each browser tab as an app. This is the default but it can be easily reverted in the Chrome settings. We prefer to have the tabs and change tabs in Chrome.
In case you are in Europe and have an unlocked HTC One M8, we recommend that you go to settings/about/software updates and check if your phone got a download notification for the Lollipop. Make sure you download it via WiFi as 780MB is quite large chunk for a limited data plan in 3G or 4G. 
