some issues you pointed at are indeed at the current time annoying issues which can be solved to some extend with available workarounds which are in the dedicated forums.
the big relief is, that the Blender developers are listening to Users which report such unwanted issues and the devs are already tackling those issues for example;
since a few month there is a UI Team available which optimizes the UI.
and ugh I also hate the way the texture system is build - so unoptimized in some cases that it can make a person go insane.
for the pointed performance issues there are works going on to solve them by optimizing the dependency graph engine and a tiny glimpse of it is already available in Blender.
http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.70/Threaded_Dependency_Graph
due to pixars opensubdiv implementation there are also some speed ups going in for the Viewport and for playback of Animations.
there are vague estimations that opensudiv in Blender might be even showcased on siggraph.
when it comes to making 3D art, AMD cards sadly aren´t a good choice or even a choice at all, they still haven´t gotten an working equivalent for cuda, due to such an important part missing, you are pretty much locked out of almost all available GPU rendering solutions because cuda is a standard in GPU rendering and In case of 3D creation there are more and more tools emerging like 3DCoat whichbenefits of the cuda acceleration.