Tread carefully with Unity, at any time they could decide again that you just pay them for each install, even past installs. Map looks classic though, I imagine fast paced arena shooter action taking place there.
On a more serious note its really fun and easy. If you're nervous watch a few YouTube videos or take one of those online courses at GameDev.tv that just shows you around and how it works.
Great! If its rough it means you're learning! I'll check it out. Dont forget. Those skills are transferable* so the next time Unity decides to back charge for every download you can jump ship without much worry. Just focus on the design, take what you can in abstract, and you'll just keep getting better.