Disadvantages:
less autonomy in some business decisions (franchisees generally have to operate the business according to the franchisor's operations manual);
restricted territory in which you may operate and/or promote your business;
ongoing payment of fees to the franchisor;
less control if you decide to sell your franchise business as there will be a set of procedures for you to follow, including getting the franchisor's approval of the buyer;
if you sell the business you will usually have to pay a fee to the franchisor as outlined in the franchise agreement;
restraint of trade provisions on the sale or termination of the franchise that may be more onerous than required if a non franchised business is sold;
at the end of the franchise term, the franchisor is not obliged to renew the franchise, in which case the business and its goodwill revert to the franchisor.