As promised, Microsoft has started the rollout of the Windows 10 Anniversary Update today. This will be going out in stages to all computers running Windows 10 (and that's more than 350 million devices as of the end of June). Because of the slow rollout, you're probably not going to see the update coming through today, but it should arrive within the next few days.
The Anniversary Update for Windows 10 Mobile was supposed to go out today too, but it isn't. Instead, it will be out "in the coming weeks" - unfortunately Microsoft isn't saying anything less vague about it right now.
The update for PCs brings with it the new Windows Ink hub, especially useful if you have a stylus to go with your device, an improved Start Menu, notification syncing, Cortana on the lock screen, as well as extension support for the Edge browser.
The Anniversary Update is free for any device that's running Windows 10.
I'm pretty much comfortable with the fact that w8.1 is stable and not giving much headaches in terms of frequent updates like the w10., that's why I'm still here.
If booting very slowly, check your BIOS and make sure you're running UEFI instead of older PCI. Changed one machine from 3 minutes boot to 15 seconds for me.
Please re-install your Windows, defrag your HDD or clean your PC's junk using CCleaner