I've only seen bad news (in context) so far. Sustained revenue and good profit figures, or sustained WinPhone8 market share, or any kind of hard numbers for Surface sales, or news of increased PC sales YoY would make me change my mind. Right now it feels like MS is playing the PR game to hide all of those things, because they are bad.
Honestly Windows 8 isn't even that much of an upgrade over Windows 7. All I have noticed is the slightly annoying tiles you get in the beggining of starting up your computer. But Windows 8 isn't a failure or bad just because it isn't selling as fast as Windows 7 otherwise if that was the case then I guess you could say the the PS3 is a colosal failure and don't even get me started on the software sales compared to PS2.