You're not quite done! Great design doesn't happen in a vacuum. If you've developed your theme for private use by a client, then you've probably already gone through a rigorous process of feedback and changes during the theme's development. But if you're developing a theme for commercial sale, free distribution, or even just for yourself, you'll want to get some feedback. How much feedback is up to you. You might just want to e-mail a handful of friends and ask them what they think. If you plan to widely distribute your theme freely or commercially, you really should offer a way for people to review a demo of your theme and post comments about it.
At first glance, if you're happy with something, you might not want anyone else's input. Having to hear criticism is hard. However, there's a scientific term called "emergence", and it basically dictates that "we" is smarter than "me". It's the basis behind a lot of things, from how ants form food routes for...