The ease of use, it is very easy to get your bookings up in no time at all! We have been using travel PD for over 3 years now with great success - we can't really think what more could be asked from them or would make us not want to continue our successful partnership? Nothing so far that I am aware off but if you are looking out there then they do offer lots of add-ons (which i haven' t used) which makes me happy as well because when u pay monthly its good value compared too other providers who charge per ticket/ booking etc each month!!