I like that we have one platform for all our clients, this makes it easier than having different platforms per client - no more double billing! The interface is not very user friendly or intuitive but with some training you get used to everything quickly enough (we are still learning).
We started using Sagitaz because of their excellent support team who helped us set up an accounting system in less then 3 days after signing contract. They were also able to help me integrate my old Sage software into theirs so now i dont need 2 systems anymore as well which was great since im working remotely from home most times anyway :).