The best way to answer the question so there is no confusion is like this. Jomscoail was created way before mobile devices were invented. We have keeped up with the introduction of mobile devices and our product is responsive and works on mobile phones, I only have IOS devices so i am specifically talking about that. All features and functions work on a mobile but honestly some things could be better.
Jomsocial 3.2.1.2 (current version) is responsive and works great on IOS but it is a desktop product that works on mobile. Jomsocial 3.3 which is currently under development and expected in a few months. Is what is called "mobile first approach" which means it is built for mobile and also works on desktop (the other way around to now). my advice is to get jomsocial use it, create a great site and in a few months you can easily upgrade to the mobile first version which will take your site to a completely new level