It depends on what you're using.
I have been working with a NOVA card for many long years and a lot of stuff work correctly: programming (PureC, Assembler, Forth), editing (Atari Works, QED, Papyrus, Calamus, Interface), graphics (Vision, Gemview, Zview), videos (Aniplay, M_Player) in a far better way than on the standard output.
I have even made an adaptation of the Supercharger software to be able to display the Hercules mode (720x348) in fullpage on a mono 800x600 resolution.
Most games don't work, but hey, they mostly don't work on the TT....
Guillaume;