Jeff, thanks for the great review! You've hit on a few things that my users have been commenting on over the last couple of weeks. I just wanted to chime in to clarify a few things about the plugin.

The plugin is indeed, GPL (including the Pro version). I'm a big fan of the Open Source movement and it made sense to release it under this license.

The size of the url can now be altered in the Pro version -- you can actually use an alternate url. So, if you owned the url tav.ly you'd be able to use that for your short links instead of the full www.wptavern.com. And with the Pro version you can actually allow your website visitors to start creating short links on your awesome new tav.ly domain name! :)

I'm currently working on 2 features that might close the gap for you that will be released within the next month. The first is a Firefox Sidebar that will allow you to create and post pretty links to twitter. The second is link expiration -- when you create links you'll be able to set an expire time on them so these "throw away" links will actually disappear when you're done with them.

I hope that clarifies some of the reservations you've had about the plugin.