It is still in the early stages of development, so there are defiantly going to be some bugs. The start menu is really amazing and the way you open apps is cool. You can flick apps around the screen and it is in general much more graphical the the previous windows. As far as the cons, I have only had it installed for a couple of hour so i will take me a couple of days to see.
It is also kinda different so i am still working my way around.