The manga rocks even harder, believe it or not.
You ever wish that Seras would have just broken down and gone full-vampire at some point? Yeah, that happens.
You want to see Alucard summon his unholy legions to take on Nazis and the Vatican at the same time? Sure enough, that happens too.
You ever want to see the butler dude's fighting abilities in his prime? Yeah, he gets younger again somehow. And he kicks even more ***. o_O
So basically, the anime was sweet...but dear lord. The manga just plain kicks it up a notch.