Very critical. GNOME and KDE have two very different UX paradigms.
Usually people used to Windows opt for KDE, and Mac or older Ubuntu users opt for GNOME.
The thing is though, a golden standard DE can easily be setup to act as both. XFCE is so customizable that I've seen both DE types setup as UNIX like or Windows like workflow.
I'm not sure if KDE or GNOME can do the same because I'm pretty sure they focus on a target audience.
What are your issues with KDE exactly? I always hated GNOME's lack of standard window buttons and handling multiple windows in a Mac like fashion. Also the app menu which gives me flashbacks of ChromeOS.