You don't need a lot of work, and if I were you, I'd approach it as a learning experience for both of you. You get to learn what it is like to work with a designer, what they need for future projects, what works, and what doesn't. They get some money and a working app in their portfolio.
Your site is nice and clean, easy to understand. But you'd be amazed at what a few tweaks to spacing, font, etc can do to the experience.
I'm not saying it needs to be done. I'm not saying it doesn't. If you decide you want to spruce it up, I think you'll see some benefit, but it may be quite small.
I had the ugliest site on the web back in the day, the comments from people were that the app was amazing, but the UX was aweful. I found a designer on 99 designs (or something like that). He had just started designing. We got on quite well. In a day he had improved my site by a huge margin, and within a few weeks it was on TechCrunch. I put that down to the design changes. It made the whole thing seem more real.
This was just my experience, your mileage may vary.
I'm glad I asked here. I'll get to work on Marketing and user testing and report back here in a few weeks!
-Shiva