I've said it multiple times on this forum. But ok:
The tragedy is, that Windows 8 could be a true "No compromise" OS which would make EVERYONE happy with just four very simple fixes:
1. Include the start menu and the start button back. Add an option for what happens when you press on the start button (start menu or start screen). If you have chosen start menu, there should be a dedicated switch-to-metro button either in the start menu or in the task bar in the near of the clock.
2. Let the Desktop programs be the default for files you open in the Desktop. Shouldn't be hard, since WMP and friends are still shipping with Win 8. (Just playing a darn audio file or viewing a picture means switching through completely different GUI environments multiple times and playing a mini-adventure in W8 right now)
3. Add a Boot-to-desktop option in the control panel.
4. Start8 and others proved that links to metro apps can be placed into a start menu. There could be a dedicated metro programs group for the occasional need for a metro app without switching to the start screen first.
I am no Metro hater on ideology. But what we got currently is a mess. Even with Surface, if you want to create content, you want the desktop. And the classical Win 7 desktop beats the tangled Frankenstein mess that is in Windows 8 today.
These changes are trivial to implement (freeware does it) and with Microsoft's man power, they could be included within weeks. Announce it right now that these changes are coming with a free update. This will surely increase sales of W8 licenses - so lengthen the W8 upgrade offer until the end of February for those who would buy W8 because of the promised uncripple-desktop update. This way, ALL the PC/laptop users would be happy again. And the metro lovers would still have metro if they want it. With the above simple fixes you would have the unharmed power of the Desktop and the Metro world for content consumption within one OS, - switch between them at ease just with a touch/click on dedicated button without both worlds fighting each other constantly. A true no-compromise hybrid.
So, that's the immediate fixes for the desktop side. In the next version the appstore should be opened up for Desktop programs as well, this would solve finally the age-old problem of holey Java and Flash versions too - list them in the appstore and let them update through the appstore. Problem solved. I understand there could be a new package format needed for that.
On the tablet side the needed changes are more longterm: All the needs for the desktop should be removed there. It's stupid to have the need to navigate to the desktop control panel for additional settings. The Desktop CP should get again the full power of the W7 CP (right now you can add users only through the metro version.. yuck) and the metro version should be vastly expanded so that you can change all settings within just one version without shuffling between them constantly.
Sideloading of the metro apps needs to be possible, this would calm down developers quite a bit. The prices for the Windows Store for developers need to go down too. 20$ one-time fee for registration and a 20% standard fee and a 15% fee once the app reaches a certain download count. Stop with the senseless Apple-envy here and get real.
Expand the metro apps in ability to make them a bit more attractive for non-tablets as well. Right now they are an utter joke in this area. Many fixes can be included without breaking the sandbox one iota (multi-tasking, windowing etc.). Seriously, freeware like Bluestacks and Pokki offer a far more sane "appy" experience for the traditional Windows form factors than Windows itself does! Pokki's start menu is a far better blend of "apps" and programs for PC users than the start screen as well. The whole handling of the metro apps for multiple users needs to be fixed too, there should be a "global install" function. Right now you need to install them per user and update them per user.
Vastly expand the default apps; they are just embarrassing. Some of them look as if they consist of two code-lines. The whole metro-ideology needs to get a lot less anal too. The "design first, convenience second" thing serves no one. Stop with the obsession of hiding buttons and functions.
Start de-uglifying Office 2013 and Visual Studio 2012 immediately (colors aren't bad, M'kay) and promise free updates for the GUIs in these products. All this could roll-in with a huge "We have listened!" - campaign.