After a month of using Windows 8 on my primary computer, here are a few considerations.
Windows 8 Desktop
Windows 8 desktop experience is to all effects very similar to that in Windows 7. The new style is less rounded and has fewer transparencies (like for windows borders), but I tend to prefer it. Most everything works the same. At times, a dialog box has a Metro style (pardon, modern style) even if it is clearly a Win32 pane. Like when you share your desktop with an external monitor.
However, there are several core applications working so much better. One is the Task Manager, which is incredibly better compared to the previous one (not that this was difficult, given the previous one was really limited). See the image below for an example of what I mean:
Another one I like is the graphical throughput of large file copy operations. But there are many core areas of the product that work much better than Windows 7. And boot time is significantly faster, at less than 10 seconds (with a SSD).
There are also issues. Windows 8 most times thinks that my internal DVD is disconnected, but Dell seems to have a fix they'll release on October 26th (not sure why they cannot release it sooner...). I'm also experiencing a few severe problems, but they might be caused by hardware errors, so I'm not tying them to Windows 8 for now.
In terms of software compatibility, I had to re-install VMWare and Camtasia. Good I had the latest version, if not I'd had to buy an upgrade and this wouldn't have been great. Delphi (I have XE2 and XE3 installed) works fine and so do my Delphi applications. I did notice some changes to UAC and protection, but need to study them a bit more before I have a firm conclusion.
Windows 8 WinRT/Metro
At this point you might ask, if you like Windows 8 desktop how do you like the WinRT / Metro / Modern UI part of the product? The most honest answer is "I don't know", simply because I don't use it. Yesterday I had a tour of the store, installed Microsoft card games and another minor game. There were a number of apps I have no use for, because there are web sites I use or existing Win32 applications I use for the same task and I see no reason to change. I browsed for about 10 minutes, but there was nothing I found really relevant. I know, I'd have my kids install from the store rather then download Win32 "unsafe" apps, which they don't even know how to find. But for professional users, can you suggest a killer app for WinRT, for which there isn't a better equivalent in the native world?
Now as a person interested in Windows 8 but not much in WinRT and Metro, I immediately found it annoying having to go through the Metro desktop to run a new application and I really started missing the good old Start button. I realized there were many operations requiring me 3 or four actions rather than one or two. So I almost immediately installed one of the many "start button replacers" and I currently cannot live without it. The one I picked (and I know there are several others but I haven't tryed comparing) is called Start8 and is located at http://www.stardock.com/products/start8/. It originally had a Windows 7 start button graphical replacer, now they have changed the button's graphic but the program retains the exact capabilities of the Windows Start button, with pinned applications, groups, search, documents, control panel, and even a simple way of shutting down the OS.
It not only shows on the desktop, but it also captures the Windows button of the keyboard, and it let's you boot directly in the Win32 desktop, rather than on the Metro desktop.
Conclusion: Windows 8 without WinRT
In other words, I can spend a full day in Windows 8 without ever seeing the Metro desktop or any Metro application... and given I like Windows 8 desktop more than Windows 7, I'm very happy with my current settings. I know this makes little sense, given I'm "skipping" the most relevant features of Windows 8, but if I don't need it I prefer the freedom not to have to use it anyway. I guess these "start button" utilities will become very popular. But if this will be the case, then the Windows 8 project for desktop PCs will be a partial failure.