The latest Debian packaging of gthumb, 2.11.3, doesn't crash, but it lacks essential features found in 2.10.11, so I have held off. The most important missing feature in 2.11, from my standpoint, is a sidebar with thumbnails. Probably Debian should package both under different names, as 2.11 doesn't seem ready for mainstream use yet. The 2.10 version has been eminently usable, for my purposes.
It's nice to see the Grumpy Editor acknowledging gthumb as a photo collection manager, and not just (as had been asserted earlier) a viewer.