Honestly, this doesn't impress me. One carrier, and a limited number of phones at that - and a fee. I think it would've been much better to focus on making the online scheduling site work with any web-capable phone, like Google does on their main page, Gmail, etc. The next step would be WAP support for even more phones. If you're going to have a Java Midlet, release it openly for users to use on J2ME enabled phones.
For me this is more about marketing tie-ups with Verizon than functionality. Fine for what it is, but it doesn't impress this geek that much, sorry. Even if I still used Verizon (Several years ago, after their sales reps repeatedly lied to my face, I dumped them and switched to AT&T Wireless... I mean Cingular... no, I mean 'The New AT&T'), I wouldn't pay to use this service. I think the same resources would've been better used getting scheduling working nicely for all mobile devices, but maybe they see the marketing value as being worth developing something for one corner of the market.