I like that it is easy to use with all of my booking sites linked up! It's also very user friendly which makes life easier when you are working in different places at once as well (especially if they have differing time zones).
Nothing really - but some things get lost sometimes due to how much information can be entered into one page/screen so make sure your looking closely before pressing save!! If there were more pages available then this would not happen quite often anymore though. We mainly used their services through our website however we did bookings directly too via phone calls etc.