It looks like GTK3 UI becomes much more stable in the recently released versions, so why stick with GTK2?
I would stick to GTK2 for a while; 1.10 was planned as GTK3 ready, but I think, it is too young. I would rather wait for another wireshark release.
Apparently upstream decided to switch to Qt and abandon GTK2/GTK3 backends entirely. I think we should just close this and switch to Qt in the future.
Great (sigh). I would *not* hurry and see, if the GUI is complete. Message from Gerald about the release and GUI plans: http://www.wireshark.org/lists/wireshark-dev/201310/msg00070.html
It was fixed few releases already.