Why the hell have development team of Plasma removed one really important thing and reason why I'm using Plasma ?!!
I upgraded my Fedora to 22 and also Plasma Desktop to 5. And as I see, there is NO POSSIBILITY of having different virtual desktops ! Yes, you still can have more virtual desktops BUT they're all the same !! And there are also only 2 possible styles of desktops- folder or workspace. NO Search and Launch etc... You even can't have different wallpaper or widgets on them! Well now there is NO reason for having more desktops if they're just same.
Hope they will return this thing back to Plasma 4 'style' or I'll think about DE switch...

https://bugs.kde.org/show_bug.cgi?id=343246

tl;dr: use activities, you've been anyway, since that's been what happened under the hood (plasma mapped VD changes to activity changes)