I installed KDE (3 at the time) the first time on Solaris 10 quite some years ago – and have been a fan ever since. I’ve been using KDE as my main desktop environment on the Sparc desktops I had; one of them is currently still my main "window" (via vnc) into my development work within the Oracle corporate network. To be a little more specific, that version (3.5.7) was compiled for Solaris by Stefan Teleman even before he joined Sun, hooray for him. With a little effort, I believe that version can still be found on the net somewhere.
What I like most about KDE is its flexibility; here are some examples (with KDE4, see below for some more on that) (click on the pictures to be shown a larger version):
In the screen shot on the left, the window in the bottom left is the menu to let me change the settings, and the one to its right (bottom middle of the screen) is the pop-up menu of windows, sorted by virtual desktop (workspace), that I set the "press middle button" activity to show. Gnome offers nothing in this way unless you start fiddling with replacing the window manager or the code.
The switch to version 4 (around early 2008) changed a lot of things and,
as far as I can tell, completely broke compilation on Solaris. A
dedicated team of people have been working on porting KDE4 to Solaris
and the Sun Studio compilers (other projects are sticking to gcc/g++, which is fine, but makes integration with the rest of Solaris harder – I won’t go into this discussion here ;-), and I’m very happy to say that in its
current form I find KDE4 a more than satisfactory replacement for gnome,
and with the availablility from an IPS repository, installation is as
easy as ‘pkg install’ (well almost – see below for links ;-). I even have it on my laptop (a lenovo T60p) now,
although it (the laptop) is a little challenged by all the graphic effects and – due
to the ATI graphics chip support on OpenSolaris – doesn’t support all
the whiz-bang KDE is capable of when the adapter is fully supported.
2) If you look closely, you’ll see another example within this first example: it’s a gimp window holding a screen shot of the window switcher that I configured for the "alt-tab" action (it’s the Flip Switch, if I’m not mistaken, found in System Settings -> Desktop -> Desktop effects -> all effects). What I can’t show in a single picture: whenever I use this method of switching between windows, I get the most recent one first, so even if I selected the current window by pressing alt-tab several times, I can get back to what I was doing before with a single alt-tab. This is useful eg. when someone pings me in xchat (which happens fairly frequently since I work from home).
3) I can configure KDE to show me all open windows (with live content) across all virtual desktops and I can then select the window I’m interested in (picture on the right). The highlighted window is the one I was working on last, so if I accidentally activate this feature (in my case by moving the mouse into one of the screen corners – this is configurable too, of course 😉 it’s not too hard to "find my way back" to resume what I was doing.
It may be a little hard to see that I have two panels configured, one at the bottom of the screen that has the pager (virtual desktop selector) and holds icons for all the open windows, and one on the left side of the screen where I keep icons for things like firefox, my vnc client invocation, etc. I’ve found this separation convenient (I try to avoid icons sitting "on" my desktop, they’re always covered by something else).
KDE offers all the usual bells and whistles too, of course – the background image, for example, is my own, and was quite easy to set up.
Of course, a lot of this is eye-candy, but the main thing for me is ease-of use. I’ve described three seperate methods of window selection, and I find I use all of them (plus "click the icon") at different times. Whenever I have to use gnome these days, I feel restricted.
There are still bugs to be shaken out (eg: akonadi crashes every time I start KDE, and for some strange reason the working directory for applications I start from KDE is set to $HOME/Documents (but I can configure that per application – not convenient, but works – try that on gnome!), which breaks tons of assumptions about "home" (this is not Solaris-specific, btw)), but on the whole I’m very happy with this piece of software.
If you want to try it (and please do!), I’d encourage you to subscribe to firstname.lastname@example.org; most importantly, announcements of new versions are made there (as of today, http://solaris.bionicmutton.org:10004/ is the publisher for kdedev-ips, but the port currently changes for every new revision), and any trouble people may have with them. Please go to http://techbase.kde.org/Projects/KDE_on_Solaris for a general overview of the KDE4 on Solaris project, and to http://techbase.kde.org/Projects/KDE_on_Solaris/OpenSolaris for how to install KDE (and build, if you’re so inclined – developers are welcome, as I understand it) on an OpenSolaris machine
Correction: going through my old email I realised I mixed up KDE versions and their authors: while the initial version I used was compiled by Stefan Teleman (or perhaps I even compiled them myself – can’t remember, it’s that long ago!), that was 3.4.3 (instructions here), whereas the 3.5.7 bits as I’ve been using for quite a few years now (since 2007, IIRC) were built by Michael Lindig, look here). Sorry about the mix-up.