This Linux user thinks it looks good (genuinely)
I was using multiple workspaces on Linux in the mid 90s. However, just because a feature has been available on platform X for a long time, doesn't mean it's well implemented. Case in point: I'm currently reading El Reg on my Gnome 3 desktop and I have 5 workspaces configured. However, I almost never use them because the implementation is so poor. I used them in Gnome 2 and fvwm vastly more. At first glance, this Windows implementation of workspaces looks considerably better than anything I have used in Linux. It's still innovation if you take somebody else's idea and make it better. And as for workspaces on a spinning cube: please! I had that configured for a few weeks when it first came out because I'm a nerd and you just have to. Then I switched it off because it's stupid and a total distraction.
TL;DR The 'Linux has had this for years' argument is specious. Fair play to Microsoft for improving their product, regardless of where they got their inspiration. I look forward to giving it a go.