I've been using Windows 8 for some time now and I have to say I haven't had any issues. For a video of my set up, see this link.
http://www.youtube.com/watch?v=8Bqpd7bwCW8Learning how to navigate the new Start Screen was interesting because it was so different. However, once I got my tiles configured the way I wanted It's not been a problem. Of course, any time I ever got a new computer be it Windows NT, 2000, XP, Vista, 7, and now 8, I had to spend time getting things the way I wanted it.
Regarding switching apps in Windows 8 Metro desktop, check out this post.
http://blogs.msdn.com/b/zxue/archive/2012/03/07/win8-howto-2-switch-between-apps-or-snap-apps.aspxWindows 8 is a big jump, no doubt about it. And, it will take some training and patience to master it. PC sales are declining as the move to mobile takes off. Having a "hybrid" environment such as what Windows 8 provides will ease the transition over the long run. Unlike Apple with its iPad, Microsoft just can't dump 15 years of software written for Windows by making Windows 8 not support older apps that were written for the desktop (this is why Windows 8 sales are much better than Windows RT sales as RT will not run legacy apps). Therefore, having both the Metro desktop and the legacy desktop live side-by-side was the only choice.
Regarding the initial reviews of Windows 8, like any new version of Windows it depends on which reviews you are reading. I remember when Windows XP first came out with it's "Fisher Price" interface. The reviews were horrible. And now everyone is sad to see XP go.
I understand that CentOS and so forth are free. Free is nice. However, I've always lived by the old saying "it never ceases to amaze me just how expensive cheap can be." Someone has to support whatever infrastructure you decide to install. Make certain you can find just as much support for CentOS or whatever as you can for Windows before just jumping over.
There is nothing wrong with sticking with Windows 7 for now if you aren't ready to make the jump to Windows 8. There are a lot of applications out there, including Amazing Charts, that have not been officially tested by the vendor on Windows 8. Unfortunately, you cannot obtain Windows 7 on that super cheap P. O. S. computer from Best Buy or Staples. Windows 7 can, however, still be ordered with a brand new Dell/HP/Lenovo business class machine. And Windows 7 has almost 8 years of support left from Microsoft. For those of you who have jumped to Windows 8, I recommend Paul Thurrot's book which can be bought from here:
http://tinyurl.com/ng8y7ufPlease note there is a Kindle edition available.
While there will always be improvements to be made, I think Windows 8 is the right step for Microsoft. It will be a painful transition just like Windows Vista was with the UAC everyone hated so much, UAC which is still alive and well in Windows 7 and 8, but in the long run as more and more applications take advantage of the new features and new paradigms of design, the pain will go away and things will become more efficient. You'll be able to work behind a PC and work on a mobile device with the same application with ease. Until the third party app guys, such as Amazing Charts, catch up, we're kinda stuck in limbo.
JamesNT