I very much enjoyed this game, but i agree with smeffles it needs a better gui....so 4/5,.....and adding a button/labels in unity is really easy btw, probaly make a better gui in 15 mins.
I can appreciate the game as a first project..which i assume it is. Here is a tutorial i used for a 2d game very closely matched to this one. http://www.3dbuzz.com/vbforum/sv_videonav.php?fid=db25cc88fdc47f4afd9562b6abb1332a
Currently Learning unity 3d at the moment I can appreicate the work your put into this game,but on next release try to add more game mechanics such as maybe weapons , maybe quicker speeds, shark repllant that can be used on space bar press, random other things. I guess the other commentors dont realize the amount of work it takes to even make a simple game such as this.....if you have any questions about unity btw feel free to ask.
Thank you for your comment. Here is a new version of DragonFly Racer http://www.kongregate.com/games/DystralEuphorie/dragonfly-racer ^^ Good Day!