It's a huge improvement. M1 is a stream of flames with nothing to learn beyond the misleading weapon range. M2 does no damage on its own and has to be used creatively to get the most out of it. A bit of finesse can go a long way with the compression blast; you have to know where you want your enemy to go and aim in a way that will get them there. Sure, you can just run at enemies hitting M2 but it's hardly comparable to W + M1.
Personally, I think the airblast is fine and is in no need of change, especially one that doesn't quite fit with the nature of the airblast to begin with. It's the flames themselves that need an overhaul if you really want to 'fix' Pyro.