The ease of use! I love how easy it was for me (and my clients) when setting up each account/pet - they have made this very user friendly as well!! It's not perfect but we are working towards making improvements in their platform so there will be many things improved upon over the next few months or years depending what version comes out afterwards etc.. We actually don't really utilize much other than billing & scheduling which has been great since most people tend focus only one area anyway- however our client feedback tells us otherwise where some users find certain functions difficult if used at all i guess? Some areas such as "pets" could do better explaining why something isn’t possible like "you can NOT put your cat here because he doesn'';s allergic” rather then just saying no lol.- But again maybe thats an upgrade issue too?! Maybe try using them first before giving any negative ratings about anything specific?