The UI is great, love the simplicity, but I really don't want to use Paypal for anything. Freshbooks mails me a check or hooks up to any payment gateway I want to use, meaning I don't shell out for Paypal's fees. I'm also not seeing what this is doing that Freshbooks is not, other then having a nicer UI.
I think the key differentiation is the fact that Ballpark is built for teams. This might not resonate with freelancers (who might just use it because it works well and looks pretty), but, in most small businesses, more than one person is usually involved in the process. For example, we run a design firm (www.metalabdesign.com), and while I don't personally send out estimates or invoices, I can easily keep track of incoming payments via the dashboard, give sign off and comment, see what the numbers for the month were, etc.
Regarding PayPal: Nobody is required to use PayPal - it's totally optional. We're definitely planning on looking into offering payment gateway solutions, but at this point we are focused on polishing the core functionality and adding some really cool new features that will help differentiate us from the pack.
