I'm with you--it's hard to put the idea of upside risk out of your mind. (What if you tell the world and the world loves you so much your server turns into a pile of slag?) But try to put it out of your mind anyway.

You need a landing page that helps your target customers know that they're in the right place. That's a sentence or two that explains the problem you solve and how you solve it. It looks like you want attention from developers. I think a lot of developers would like to get a feel for the API without registering. (I went to the "developers" tab thinking I might be able to give you specific feature-related feedback.)

With that done, I'd think you don't need or want attention from the whole world. For a first round of feedback, 5-10 like-minded friends would do fine. If they're really friends, then they'll have encouraging words for you, but look for common points of confusion or concern. After that it's a matter of refining your message and finding wider and wider circles for gathering input.