I am not a KDE person. I was a gnome person. Now, I consider myself mostly an Openbox person. Now with that out of the way, onto my comments:
Disabling all effects, turning off tooltips, switching from Oxygen to Plastique themes for QT interfaces and window decorations, and using “Ember” desktop theme instead of the over glossy default “Air”, switching to the classic style menu and mostly ignoring the fact that “plasma widgets” exist has made running KDE a rather rewarding experience.
It’s still nowhere near as snappy as Openbox or LXDE, but it’s not even in the same vein and thus isn’t really fair to compare. Though, I’m impressed that by messing with the settings a bit, it can run quite speedily on my old IBM Thinkpad T42.
I still think it needs a bit of work in some areas. I get weird pre-draw static where new windows, menus, or pop-ups are going to show up. The panel width seems fidgety, my “PM” at the end of my clock is for some reason hanging half off the edge of the screen, and I think the size-setting handlebars in the panel config screen are arcane and extremely unintuitive.
I really like some of the application suite. Dolphin seems to be extremely powerful, gwenview is a really good image viewer, and all of the settings and configuration programs are a pleasure to use. Konqueror should go burn in a fire though… I find it klunky and unkooperative. Also, the “k” thing is really dumb, I’m glad that it seems they’re moving away from that.
My feelings are that 4.7 is a huge improvement over previous versions which I found prohibitively buggy.