There really are not any downfalls, unless you're a web designer seriously into doing your own database stuff, etc. Most people aren't, including myself.
With a little imagination and creativity you can do anything you want to with it. The SBI team keeps churning out new tools and additions to it, all at no extra charge to us. If you want your own store, that is extra because it's a completely different animal.
It just keeps getting bigger and better.
