Yes. You can't buy iTunes gift cards with it.
Customers may not redeem their store credits: (1) at any iTunes Store in the United States or elsewhere, (2) Apple Store locations outside the United States; (3) at Apple resellers; (4) for cash; (5) to purchase Apple Gift Cards, or,iTunes Store Gift Certificates, to give iTunes Store content as gifts, or to create iTunes Store allowances; or (6) as payments on Apple accounts.