I know a lot of people hate KDE because of the early 4.x builds. It has gotten a lot better now, and it's constantly getting even better.
If this is the case, he should take it for a spin. I find that it's the most customizable and user centric DE around.
There are a lot of settings you can tweak, probably too much for some, but I know each time I test Gnome/Unity/Xfce/Lxde/Cinnamon etc. I miss a lot of easily accessible settings.
The community is also great, there is a saying: KDE is the community, not the software.
Last time I tried to use it, it had plenty of options, just not the particular ones I wanted.
I generally like a very minimal interface along the lines of Openbox. Right click for menu, middle click for window list, windows minimize to desktop icons, scroll wheel cycles through virtual desktops. Maximized windows don't cover a few pixels along an edge, so I always have access to the desktop. The only taskbar type stuff visible is a clock and the system tray, which on the computer I'm using right now auto-hide in the upper left. (I optimized for screen space on a netbook that didn't have any, and found I liked it anyway.)
I'm happy to spend a while wading through settings to get this set up as I like, but KDE won't let me (not that I really blame them). However, I do find it annoying when it's billed as the most customizable DE out there. In terms of the color of any particular thingamabob, absolutely. In terms of major differences in overall layout, not so much.
Xfce and LXDE have always worked flawlessly for me.
FWIW, I liked KDE's early 4.x builds. I thought it seemed like a major improvement both functionally and visually over 3.x.
The only problem is, I've never been able to use KDE for longer than about a day before experiencing major (read: show-stopping) performance regressions and severe crashes (read: listening to music while programming, suddenly whole desktop disappears and it drops back to the login manager, or I'm beset by dozens of dialog boxes about SIGSEGV errors buried in 30-thread spaghetti messes while my music mysteriously stops). I've also run into serious data corruption issues where something nuked the Nepomuk databases or something else nuked the Plasma widget configs.
As a result, I've found KDE 4.x completely unusable. I try it now and then to see if they've fixed anything, but as of 4.10, I still can't use it for more than a few hours without something blowing up.
So, to me, the community is irrelevant if the software is useless.
I used to use KDE, back when I used a Linux desktop. That was in the 2.x days.
I even used Konqueror as my main browser (circa 2000-2002) -- the alternative was the unwieldy Mozilla.
So, here's an observation about the community: back then, I read dot.kde.org (the official "KDE news" blog), and it would fill with 10-15 news stories every day or two. Each story would have a 50+ comment thread. Now, if you go there, there are one month old stories in the first page, and most stories have zero or 1 comment.
I don't know about the use base, but the active community has definetily shrank.
(There were also tons of announcements, new projects, theme sites, interviews with KDE hackers, this Mosfet guy, the Kompany, etc etc).
You mean like KDE?