I have actualy tried out the Windows 10 Technical Preview, it has been pretty buggy and the start screen or taskbar sometimes become un-usable for a few minutes, but that probably cause i had an older tech preview. Microsoft has really been advancing with Satya Nadella as the CEO im not saying that cause im indian. Satya loves linux unlike the other 2 foolish former CEO's, Now Microsoft is opensourcing .NET on Github, DirectX Seems AMAZING(If only it was cross platform like OpenGL), New Visual Studio 2015 and Visual Studio Code(For Linux,OSX,Windows) and not only new products such as Holo Lens and the New Visions of Run Everywhere, Microsoft is really going somewhere.
I have to agree that Windows 10 is probably their best yet, far from perfect as it is buggy but that's what happens in alpha/betas so its normal - I am looking forward for its release and developing for it.