nouveau is certainly more often problematic than radeon in current days. informer i had to fix myself a bug within mesa and some oem cards which are less popular (like x700se which showed a checkerboard first). nouveau however likes to crash the system often badly. also when used with llvmpipe the system likes to crash as well, no idea why (especially with pci-e 3.0 and kelper, did not happen that often with pci-e 2.0 and the same card). nouveau.modeset=0 is often needed, one card that is pretty popular and needed that hack with the default 3.2 kernel (precise) was btw. the nv gtx 550 ti.
i do not understand why there is no fallback possible to work without compiz on ubuntu, i do not like the whole unity thing as well. marc hold a presentation a few years back at linuxtag where he showed slides how he wanted to have got the next ubuntu interface, the first thought was definitely that it was optimized for small netbooks or tablets. i still do not see the huge benefit of that ui for standard desktops. of couse the name implies that it should be used everywhere - a similar approach is done by windows 8 - both changes are not seen positive by everybody.
btw. kde allows the use of ";" in desktop icons gnome 2 did not, no idea about gnome 3. i really like to use more than 1 command without writing a script.
unity is a special case because no other distro ships it by default, so ubuntu has to fix all bugs basically on their own. i am no fan of gnome - maybe the first version was ok, but as soon as kde 2/3 was out i never used gnome. i tested gnome shell very shortly and i disliked the fact that i could not create desktop icons anymore. well there are dconf hacks but i speak of the out of the box experience. every DE has got its bugs, so basically have to select one that has got the less important ones for your typical workflow. if raw speed for games is important unity does not seem to be that good - but a real gamer usually has got a faster gfx card and it should not be important if a game runs at 200 or 60 fps - most tft are displaying not more than 60 anyway.