Honestly JomSocial looks like it'll be a good addition to the growing Joomla community.

However, you must keep in mind that CB is in a stable and progressive state already. As well as the large community backing. Many popular components already have CB integrated into their core.

Then you must compare the APIs. You have to decide if you want a more complex and flexible API (CB) or if you want a more simplified hardcoded API (JomSocial).

JomSocial does have a beautiful layout. However you can't ignore the easy of creating such a layout for CB either. As CB layout is driven by CSS leaving the power to display it however you please in your fingertips. A good layout out of the box is great, but do you want to look the same as everyone else?

Remember a pretty layout makes not a functional site!

When comparing to other platforms you must always keep in mind the current time that CB has ahead of these new platforms. JomSocial and many others like it are in their first beta phase or not even past pre-alpha. While CB has stable releases. As the others continue to grow. As to will CB. I can only see the others "catching up" if they have a rather large team with good financial backing.

The next is cost. JomSocial is not free, period. You have to pay to use it. That's all there is to it. You do not have to pay to use CB. You do if you REALLY want to experience the new version before it goes stable, but you do not HAVE to pay to use the product.

Not everyone can afford the luxury of throwing money at each and every companies way (With all the great commercial components. Then you add in your platform. The numbers start to sky rocket). So 1 less forced payment is always a good thing. ESPECIALLY if it's your platform.

A social network site takes many many hours of hardwork. You'll get no easy golden brick road with EITHER CB or JomSocial. Whatever you decide to go with. Just be sure you have the time and ability to dedicate to that platform. It's no easy task to develop a full site then jump platforms. Once you've began production and have a user base. Changing is not an option.

I foresee many new users giving JomSocial a try if they're willing to pay to try it. However all currently developed and advanced CB sites I do not see making the change at all or any time soon.

To put it short. They're both good platforms with different objectives. I urge all to stick with CB as our community helps keep us strong. Jumping on the forums with a question generally gets you an answer. JomSocial is a new beginning with no community. Finding answers to MANY of the early problems will likely not be an easy task. So for beginners your best bet is to just stay with CB. For those more advanced then sure go ahead and give it a try.

I wish JomSocial the best of luck, but for me CB is my platform and that won't be changing.