I used the Gnome flashback at its inception, when it was called "Gnome fallback", and I had the impression that it was a hammered product.
I'm still very skeptical of it, because I think it will be always a second-class citizen.
In particular, it is a paradox in itself, since it's used by people who refuse the Gnome direction, but it's maintained by people who are into the Gnome direction.
I think ideally G.F. efforts should be directed towards MATE, although of course, that's not realistic.
I agree that it's second class but it works and that's what matters. It was a little worse than Gnome 2 until 16.04. They improved it quite a lot at that time and I can say that I have back my Gnome 2 desktop now. I hope they keep it in the next Gnome and Ubuntu releases. I hate DEs with a top bar (MacOs, Unity, Gnome 3 among the others) because it steals space in one of the most important places of the screen and it gets in my way. Among the DEs I somewhat like only Gnome Flashback lets me move all of its contents to the bottom bar and delete it.
I'd advice to have at least a brief look at MATE, since its whole point is to maintain the Gnome 2 feel. They're also receiving truckloads of money, so there's lots of manpower behind, but the most interesting thing is that they took the opposite direction of Gnome 3 - they're giving a lot of flexibility to the users (see all the panel options at https://ubuntu-mate.org/blog/ubuntu-mate-artful-final-releas...).
I'm still very skeptical of it, because I think it will be always a second-class citizen.
In particular, it is a paradox in itself, since it's used by people who refuse the Gnome direction, but it's maintained by people who are into the Gnome direction.
I think ideally G.F. efforts should be directed towards MATE, although of course, that's not realistic.