Like Kemical, I am 100% comfortable with Windows 8. I believe, with sincerity, that the only mistake MS made, considering it a new product with a different look, was to drive a new user straight to the so-called "metro", rather than let them dabble their feet in the shallow end first, by taking the initial boot straight to the desktop, old start menu included. Had they done this, perverse as we humans are, their would, possibly, have been complaints about the extra click to get back to the Metro. One rumour in the "blue" saga, is that it will, indeed, be a choice.
But, notwithstanding, Kemical's phrase, "but many users especially coming from XP simply see the learning curve as too steep." was the most significant blow to Windows 8's future. It is now historical, that Vista had the same experience. I was fortunate enough to fet onto the Vista Beta testing program, this gave me an early insight into its, rather dramatic, differences from earlier OSs, which led to a position of strength, in the help field. But, with that particular program, the acceptance, or, rather, non-acceptance, was from a different area. The manufacturers, across the board, di not cooperate quickly enough to the new requirements for drivers, and compatibility quirks in programming. As a result, Vista was marked down as a disaster. In that instance, Microsoft covered their losses by bringing along the much improved Windows 7.
It does look like history is repeating itself with the rumoured "Windows Blue". I have had the chance to look at some of the latest builds and would argue that it is not, as referred to by the media, a service pack. In my mind, maybe splitting hairs, a service pack is something, large or small, which arrives via updates or notification for download. In this case, Windows Blue is, in fact, a complete and self standing OS.-
I will, whatever, find any improvements welcome, but I would add, as an experienced user, that I will always regard Windows 8 as a dual purpose OS. You may elect to use it as a desktop or as a more portable, possibly touchscreen /Tablet OS. It is unlikely, in my limited future, that I will ever use a tablet, except to help out my children/grandchildren, but, I will, as said previously, continue to use the OS, only for it's modest performance improvements.