I am user of Appointment Booking Pro since 2010 and am amazed by the product. It is as good as any paid hosted appointment solution available on internet. I am running it for over 2 years now and it is a smooth ride. Now we upgraded to J2.5 and really delighted to see the one thing it lacked back in 2010 was SEO is now accounted for.
As good the component is the support is even ahead of it. I felt very guilty of writing number of emails to support but Rob Stevens was very supportive and accommodating. Never came across such a level of commitment from any vendor. Thank you for all the good work!