"[Plasma] works quite well already, although it crashes from time to time and then my plasmoid settings are not saved."
periodic saving will be implemented, though possibly after 4.0, depending on how a few other items go. i don't want to repeat the mess we had in kicker where applets would sync() various different files (2 or more per applet in some cases) on every possible change. that's not nice on the disk.
we now share one config file per corona, so this opens the possibility of one global sync(). what's missing is a way for applets to tell plasma that they would like a sync to be done. unfortunately the KConfig classes provide no notification on local change nor do they even provide a way to tell if the config is dirty (that's part of the private API only). so we need to provide a way for plasma plugins of various ilk to request a config saving. then plasma can schedule one (probably with a short delay in case several requests are made in a short timeframe, something that is fairly typical in various situations).
as for crashes, please send backtraces of such events. =)
"If I log out and log back in plasmoids lose there rotation setting."
known issue; the rotation is saved but the restore code is broken currently. my bad.
"The panel is not configurable yet and I have problems removing applets therefore."
will be addressed soon.
"KNewsticker, which is actually in extragear stresses my CPU quite much here, since the animation seems to be completely done (I can remember the same issue with the KDE3 applet) without graphics acceleration.
it has nothing to do with acceleration or not and everything to do with the fact that QGraphicsView's clipping implementation is currently quite simplistic to the point of naivety. this causes massive amounts of unnecessary repainting when clipping objects (among other things, such as some interesting event propagation issues). fortunately Andreas knows all about these issues and is working on them. by kde 4.1 we should have a better behaved clipping implementation, if not sooner.
"I am also a bit confused since plasmoids claim that OpenGL shaders are not supported here. It is right that Intel chipsets (at least <965) have no hardware accelerated shaders, but I can at least render stuff, e.g. Google Maps, Nexuiz, VDrift here, even if they perform badly. So in my opinion that should be configurable, since small OpenGL animations would work.
if you don't have shaders, and the applet uses shaders, there's not much that can be done except rewrite the applet to not use shaders. Plasma::GlApplet does not require shaders itself, but some applets, such as the bluemarble 3d globe (no relation to marble, the kde4 mapping widget, btw) do. so you can use OpenGL applets on your system .. just not the ones requiring more advanced hardware and/or drivers.
hope that clears a few things up.