1) KDE does still have some bugs, but Arch is another meta-distro and it's not known for it's stability. Most people who like KDE use SUSE, while a lot of others use Kubuntu - both of which supposedly have better KDE experiences than Arch. Source distos (Gentoo, Arch, LFS) are never more stable than binary distros. Although I will admit that's the fault of KDE, not Arch. It's just hard to simulate how things will compile in a 100 different configurations.
2) KDE's base is superior to that of GNOME. Still having to use GConf Editor in 2010? Seriously? Which brings me to the next point:
3) Don't ever say eye candy and gtk in the same sentence. QT is so much more advanced than gtk it isn't even funny anymore. In Gnome you still have the same themes installed 4 times because gtk doesn't support color themes as well as QT does.
Both KDE and GNOME have problems. The question is, which problem would you rather have: A lack of maturity (KDE), or a lack of features and innovation (GNOME) ?