Over rated mostly because people put the flat tappet down for the wrong reasons. No doubt the roller is superior in most cases. I just think people get hung up on it for the wrong reasons. I sure would not let it sway me on a block decision.
I have several FT cams in cars right now with no issues. I'm not against FT cams. But here are my main 3 likings for the roller.
I can buy a 5 qrt jug of 10W-30 of my choice for cheap and pour it in the roller cams. No "high zinc" like VR-1 or Royal Purple or additives.
I can swap cams in my roller motors and use the same lifters. That is very nice! In fact, I put a re-grind cam in one without changing the lifters making it actually more affordable than swapping flat tappet cams.
Also, it is VERY nice not to have to prepare for the "cam break in".