This was the single change that I most wanted to see in Pokemon, particularly after gen III introduced so many pokemon with mismatched stats and typings (Absol, Shiftry, Sharpedo...) or dual types with one physical and the other special (Breloom, Camerupt, Altaria...). I clearly remember thinking how awesome it would be if there were both physical and special attacks for each type so that, for instance, Gyarados could finally get a decent water attack or Absol could actually use Swords Dance and a STAB attack, so I was thrilled when they actually did it. And it's turned out to be everything I'd hoped it would be.
And I always think that this is a thing that should be taken into consideration when people start criticizing DPPt. As the generation that introduced the physical/special split, I think it stands tall immediately, just for that reason alone. Everything beyond that is bonus.
The only sort of disappointment connected to it is that it's made it that much more difficult for me to replay anything before the 4th gen. I've been doing a Nuzlocke of Sapphire lately, and it's okay, but I really notice the difference.