I think this was a really good summary from Top Gear.
"Overall this is an improved vehicle. Quieter, roomier, more generously equipped and less wearying as a GT than the old M2. That’s a crowd-pleasing move from BMW, but the die-hards in the mosh pit don’t want an M4-lite. They want an M2. Now it’s bigger and more grown up just about everywhere, what the M2 lacks is a personality all its own, which the uncomplicated, uncompromising old M2 had in spadefuls.
If we were a current M2 owner, we'd be feeling pretty smug that our car looks prettier than the new M2, has a more intuitive (if less plush) dashboard, sounds fruiter, and goes with more poise, more purpose, more sense of being a barely contained ball of fury straining to escape from a working-class hero chassis. Perhaps that was where the era ended after all.
That said, if you’re looking purely at new car options, the M2 really is in a class of one. No other small sporting coupe is as practical, and in many ways the M2 now asks very serious questions of the M4 itself. There, we just saved you £18,000."