I'm playing San Andreas on Xbox...100% noticed the frame rate drops but it doesn't make the game unplayable. I have no problem with the art style either....
But in reality, I rather play GTAV again if I want my Rockstar/GTA fix....
Though...GTAVI should have those ambulances, drive around side activities...because I like them.
Oh, and the checkpoint is much needed and great.
I know GTAIV is not working correctly in backward compat mode.....the framerate is too high so the last mission is almost impossible to beat because it requires button mashing. I believe when you hit the button, the high FPS makes the game not register half the amount of presses you do.
I might not need complete overhaul for the older games....but checkpoints is a must. Makes the games more enjoyable.