What's missing (in custom order)
- Menu Start (of course). Shortly - I miss it. But not as much to have 3rd party one.
- Aero glassy windows. New plain windows are not bad, even nice, but I liked glassy ones.
- Flip 3D. It was very practical way to find some open windows deep on the bottom at the end of business day.
- Recovering files using Previous versions tab. Yes, we people do not need to recovery files - what a stupid MS idea. Hopefully in last years some cloud drives services appeared with recovering options. But still - you may have some (especially large files) out of cloud folder.
- Shutdown button - yes, there is shutdown button in fact - somewhere ;)
- XP mode. Free virtualization enviroment (with legal Windows XP) had its value. Too long.
- Windows Media Center and DVD codec. Now you have to pay more for features which was in standard. For a while you may had free Windows Media Center license - but it was time limited offer.
- Desktop gadgets - a big idea of tiltes in menu screen killed them - but it's not the same, titles are useless as they are only in menu screen and not on the desktop where you spend 99% of time.
What's new (in custom order)
- Tablet mode - another world, messy, stupid applets..
- Internet Explorer in tablet mode - OK, sometimes I use it, while eating dinner, and only one hand it's free - but it's like browsing Internet sitting in a cage.
- Ribbon in file explorer - useful sometimes..
- Upper folder icon in file explorer - big missing feature in Windows 7 - there was ALT+upper arrow shortcut in fact.
- Stacking file copy windows with bandwith graph - nice - but still - is "better files copying" a number-one-feature in new version of Windows? - hey, we have XXI century!
- Welcome screen/lock screen with wallpaper, clock and weather cast - nice.
- WIN+X shortcut with admin tools - useful, especially when you cannot go into (not existing) menu and click right on "computer".
- Marketplace - echo, echo, echo.. oh! there is something in store.. expensive and useless..
- "Intelligent" scaling of remote desktop screen - the one feature I really like and it's really usefull in my admin tasks.
- New bootloader - it assumes that you'll choose Windows 8 - what's true in most cases - so it does not wait for your decision and loads Windows 8 in "background" - so it save some seconds on booting time - and loose them if you choose another system (need to shutdown Windows 8 and reboot).
- Some "return to factory setting" tools. I have no experience with it. I do not trust.
- Extended and colorful Task Manager. I like this new one but I don't use it to often to tell it's "must have" feature.
- Mounting ISO as virtual drive. It's really nice to have it without 3rd party software. But also I'm used to double-click on ISO to have it burned on media - so I still make this mistake playing with ISO files.
- Panorama wallpapers/themes (spanned on multiple monitors) - nice.
- Hyper-V. Nice, but still - XP mode is missing.
- PDF reader (tablet mode) - in theory you don't have to install Adobe Reader. But in practice - I hate an MS idea to open files (while in destop mode) in tablet apps.
- Image browser (table mode) - as above - bad idea to have it as default JPG reader. Some additional clicks needed to have JPGs opened in old desktop picture app.
Summary
Windows 8 - is a very cheap downgrade from Windows 7. New features would be a reason to upgrade, but you loose as many Windows 7 important features, and you'll need to face a messy hybrid tablet-desktop world.
I'm waiting for Windows 9 - hope it won't be the first Windows without windows (desktop mode).