OK, fine... I'll be honest...
I have had good experiences with it. I have not had problems with apps. Most of my apps I get via Obtaininum. As for the UI, I think it is fine.
I don't think Google will be able to lock my Pixel's bootloader, and, if they do, well it is already running the OS. So it shouldn't be a problem for a while. If at some time GrapheneOS stops being supported I will find something else. I don't need a guarantee of permanence to find it useful today.