I dabbled in Linux for awhile, then switched full time to Ubuntu some years back. I wanted to run some specific games and switched to Windows 7 for awhile, until the hard drive crashed and am now back on the latest Ubuntu. I went from Unity to plain Gnome3 and now am on Cinnamon. And yes, I think the open source desktops are losing competitiveness. I personally think at this point in time OSX is the only one keeping things together. Windows 7 is actually very nice but Windows 8 looks like a train wreck. But for Linux it seems like your choices of desktop environments are either stuck in Win95-era or prior feel, or you have a "modern" DE that's half-assed at best and takes a ton of work to make it usable.
Speaking mostly for Gnome, but the colors, themes, icons...they always feel like they're missing that extra polish or something that you get from the commercial OSes. Everything just feels...clumsy. It may work, but it just isn't polished. And while I appreciate pushing new innovations both Unity and Gnome3 seem to be halfway there at best, leaving sort of mostly working setups.
Thing is, with Compiz and the wobbly windows stuff, it actually looked pretty sharp. Honestly, I think the more things I try the less I know what I want, just that what I have isn't exactly what I'm looking for!
Just my $.02.