Let's see... on the LUMIA 635 I've been using for testing from the beginning, the performance is about the same (dismal compared to WP8.1). Apps still crash randomly (especially native ones, curiously). I already have two apps that will NOT update in the Store: LUMIA Help & Tips and Motion Data (both error 803F8006). I was up to eight apps with various errors trying to update. I expect no different with this version. I usually see "resuming" after swiping up the lock screen (and I HATE the new way the lock screen works... stupid Microsoft). Edge is still incredibly slow to start and takes forever to completely load a webpage so you can navigate it (the same problem exists on the tablet/desktop/laptop version). I don't even dare using the SD card anymore because support is simply a flip of the coin. With this latest version the radios don't work correctly. After a reboot it takes up to five minutes for the LTE radio to work and up to ten minutes for WiFi. This NEVER happened with WP8.1. Although it was always slower on W10, it was never this bad. The Camera app automatically forces landscape rotation when you first start it (stupid). When playing back a video you recorded the volume control has a long delay before responding (I attribute this to just the overall HORRIBLE performance of W10M). The Camera app also never remembers that I have it set to Pro mode. Fonts on the tiles are far too small -- they are MUCH more readable and attractive on WP8. Likewise, it appears that the idiots at Microsoft are also changing the way they display outstanding notifications on live tiles, going away from an obvious and readable bold number to a teenie tiny number buried in a stupid black circle--again, hardly readable. Clearly, Microsoft is determined to make the OS as ugly and unreadable as they can. The Photos app is also still quite lame compared to WP8. The ONLY pictures you can save as a favorite are ones physically stored on the device. AND you cannot actually save a picture from your collection TO your device in order to SET it as a favorite. If I were king for a day, I'd fire Satya Nadella and all his cronies.