You need to be real strong to break from his shadow or fast enough to outrun the shadow. Neither of which Hinata has shown. Also Shikamaru is a lot smarter.
Smarts/=/ power, and Hinata wouldn't need to "outrun it." She's not melee only. She has air palm, which can damage an enemy's organs from a distance and is invisible to normal eyes while Shikimaru's shadow's (not counting in external factors) are predictable. Smarts are primarily involved with prep.
A databook fact is that air palm is a variant of palms rotation, so more likely than not, Hinata also has rotation.
When it comes to fighting strength, Hinata's better by far, and is not stupid either as her intelligence was ranked equal to Sasuke's.