Yes, that criticism is valid regarding regression. I don't have any defense for that other than it should be fixed.
As for the hinting, I'm hoping someone from GNOME can jump in and talk about the fonts. I will admit that I don't have any particular defense as I've stated above. You shouldn't be having to mix fonts of different metrics. That's wrong. We can't do anything with the interface now as we are past the visual freeze. We can address after the release. In the mean time, please file bugs and state your opinion.
If you're interested in helping improve the experience then you need to file bugs.