I found it fun! I stopped at level 8, at which point the game doesn't have much challenge left in it. Given a few more things to do, I would definitely still be playing. I do think part of the fun comes from not really knowing where your towers are going to end up and the golf swing mechanic is pretty good at separating your intentions from the results.
I would like to see more tower and enemy types and some higher contrast in the visuals. A tutorial mode (or just some more instructions in the game page) would have given me a smoother start.