Well, I tried GNOME ver 3.0.2 on OpenSUSE & found it quite stable (zero crashes). Plus, ver 3.2 is said to be much improved.
So, I feel GNOME-shell is both ready & stable. I just hope the extensions with which Mint 12 ships GNOME-shell do not affect it's stability. [ The Mint team's 'mintification' of GNOME 2 rarely introduced any instability (except for applet crashes in Mint 11) - I reloaded Mint 9, which has been stable and snappy so far.]
I understand why GNOME-Shell may be disliked at first. (Initially, I too hated it.) But after a quick, easy learning curve, it became my DE of choice. Just like KDE 4.0 had some 'teething troubles', GNOME-Shell too needs some 'sandpapering'. But if you truly hate GNOME-Shell, try KDE (ver 4.6.5 is awesome) or XFCE (ver 4.8 had several bugs, but the version shipped with Debian Squeeze, perhaps XFCE ver 4.6.2, was rock solid, although a tad minimalistic).
Overall, we can be happy that we have choices ,right ?