That's best kind of magic. Powerful because, well, power is cool; and limited because the more restrictions there are on it, the more interesting magic becomes.
Ursula LeGuin's Earthsea trilogy is still the peak of magic in fantasy, because her system was both powerful (magicians could do just about anything) and limited (everything was bound by two great rules). In Roger Zelazny's underappreciated Jack of Shadows, the Powers are only great within their own domains; and the nightsiders pay for their immortality by being soulless.
For every advantage, a disadvantage. Nihil gratis.