In that blog he links to the slides of his FOSDEM talk. I unfortunately did not attend that talk, but slides gives a good idea on what is happening behind the scenes at LibreOffice. It gives the impression that a huge amount of work is done by a large group of people.
LibreOffice might not work nicely at the moment, but all this code maintenance hopefully will result in nice improvements in their applications. I use Microsoft Excel a lot and last time I looked, Calc is really lacking (features, keyboard shortcuts, etc).