I own a brand new Surface Pro 3, and if  all the good touch features of Windows 8 are removed to make Windows 10 placate non-touchscreen users, I and others are going to be very disappointed.  Many websites are reporting that the new Windows 10 "kills the start screen" and more or less abandons all the good touchable features of Windows 8.  As one who's used windows since XP tablet PC edition, through Vista and 7 on touch screens the start menu sucks on a touch screen.  So here are the main questions a long time touch, and user of Surface Pro and Surface Pro 3 has for MS. 

Will Windows 10 that I have the keyboard attached and a mouse and in that mode it makes some sense to have the start menu?  

Will Windows 10 give those of us using a tablet such as surface pro as a pure no compromises tablet including a start screen with big touchable tiles? 

Will we finally be able to switch between all applications by swiping them in from the left? 

We will still be able to access a big touchable charms bar to find everything or will we also revert to a mouse centric control panel? 

Will Windows 10 be a free upgrade from windows 8, at least for those who bought Surface Pro 2 and 3?

Will there be a Windows 10 RT?  Will there be windows 9 RT/Phone for ARM based platforms and Windows 10 for x86?  Will metro apps (everyone still calls them that) work on both? 

How well do common scientific programs run under this OS?  In particular are Java based applications still going to be tiny on a high DPI screen? 

I intend to install Windows 10 TechPreview on my Surface Pro and then inform you of what it is like to use it.  (First I need to backup my SSD to a reliable external SSD.  I needed to buy an SSD for backups anways.  I may just try installing it to an external USB drive or a separate partition.) Then give a first hand account of what it is like to run this OS on what should be the most favorable hardware for it. 

There are some hints of answers to this, but it is one thing to see a presentation and another to actually try and do useful work with an OS.  
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Here are my first observations. 

If you have a PC with windows 8.1 and probably 8 you may upgrade directly from Windows 8.1 and keep all your files and settings.  My install of office is still available and working.  

The one feature I said I wanted in the next Windows is in windows 10, that is one coherent way to switch applications.  To get a expose like view of applications just swipe from the left.  

I have encountered only one flaw.  In Google chrome 38 which is also a beta I can't seem to add images right now... that could be a chrome issue.  

Just to test it I loaded up a game called Napoleon Total war.  It is a 3D simulation of strategy and tactics from the time of Napoleon.  The game runs without issues. 

So far so good. 

One more observation my wifi issues with the Surface Pro 3 are solved by this build of Windows 10.