While calling the wizard's spell memorisation system in D&D mana-based is tenuous, you CAN say that the sorcerer's system IS mana based.
Essentially a sorcerer in D&D uses mana to cast spells, with each spell costing one "mana point". The difference is that they have nine mana-pools to draw on, one for each level.
I do find people's knee-jerk reaction to a mana system amusing. Mana systems can be so varied that simply saying "it's a mana system, it'll be crap" shows how shallow their reaction truly is. It's not as if using a mana system means you'll suddenly get Diablo-like magic being spam-cast near infinitely. Not if you don't want it to.