I like the simplicity in telling a player, "All of your spells start with the same save DC regardless of spell level."
I don't like the higher rate that both save bonuses and DCs increase. The numbers get higher than the variance on a d20 faster than the original system.
A failed save vs. spell usually isn't a "failing forward," but just a straight up, "Sorry, you're in a maze. You don't get to play this encounter." or "Sorry, even the rogue failed her Reflex save vs. the fireball. Everyone dies." The problem with everything feeling like a success or failure is a problem with effects, not save DCs.
So if players go from expecting to save 80% of the time to 60% of the time, what that actually means is it's 20% more likely that they'll have to sit out for an hour, or spend money on healing or resurrection, or make new characters and try to re-invest in the game. That in turn sounds like preparation and non-save-based defences like immunity become even more important. Plus, martials aren't preparing or giving friends immunities anyways, so the martial-caster disparity isn't solved.