There is more than likely a whole series of vast improvements in windows 10 over windows 7 (and 8,but its not hard improving 8, taking a dump on the screen would improve that pile of poo)
But m$ have decided to hide all the extra goodness in win10 under a layer of giltzy crap.
Updates? sending data back to homebase?, a UI that takes the best from classic windows and the best(hah) from windows 8 and tries to shoe horn it together.
And then they make it free for current m$ victi.. sorry customers to upgrade.
Which says to me they're either desperate for the customer base to move to win10 and lock them in, or m$ themselves dont think win10 is actually worth paying for.
And if I'm getting an OS for free, I'm installing linux mint