I really don't understand how anyone can use Google office apps, the UI is painfully slow. I was using Gnumeric before, but I'll try this out, thanks OP!
The only two selling points for me with Gnumeric are a rough function equivalence with MS Excel 2003 and the output to LaTeX tables (which is _absolutely awesome_). Other than that, it's always been pretty buggy for me.
Not that LibreOffice gets a pass, but it doesn't crash nearly as often for me.
They have one and only one "killer feature" over various less-sucky apps - they're in browser, so it's much easier to collaborate on a document with random people on random operating systems (including mobile).
But honestly, if you care about collaborating on text and not its formatting, then I'd suggest hosting an Etherpad instance somewhere :).
Not that LibreOffice gets a pass, but it doesn't crash nearly as often for me.