I have just started using Ovatu. Online and on my ipad & phone.
I cant fault it at present, considering its free for the basic version, and only a few pounds a month for the extra features.
For me, it is important to uphold a professional image, I was spending a lot of time sending reminders, directions, information etc - Ovatu sends an email confirming clients booking, with all the details, and I've personalised with pre treatment advice etc, they then get a reminder by email and SMS. After the appointment they are asked to review, and get another follow up a number of weeks later asking if they are ready to book another appointment.
This also all links through to my Google calender (so even my husband can see if I'm in a treatment before he tries to ring me)
As well as this, I can update my social media, send mass emails with offers, and log all of my sales, discounts, regular no shows etc.
it does have the facility to allow clients to book online, although for me, this does not build enough client rapport and I feel may encourage no-shows, but I'm sure for some this would also help.
The support has been exquisite - the tech has pretty much set it all up for me, and is always there to help replying within a number of hours.
Cant fault it