Been running Win. 10 Tech. Preview for months under heavy load (about 200 tabs open on two browsers, a dozen docs, etc.) , and it has minor improvements. Seem to use less ram for one. With Classic Shell, which is also an improvement on this, then one would see even less difference.
Yet as the upgrade is sppsd to be free, then you would get a longer service life.
If you want, see my Windows 8 pro review (upgrade XP to Windows 8 with Classic Shell ) and on the Window 10 preview .
Here is what I don't like about Windows 10 - That old fashioned Left Column List of Programs. It is a waste of space and, unless it can be disabled, a deal killer for me. I like the Metro Start Menu. I use the Metro for less used programs in combination with the Desktop Taskbar for most used programs. For me that is a perfect combination.
Questions for you:
Can that Old Fashioned List of Programs be disabled in Windows 10?
Is there still a Taskbar on the Desktop?