I second that, bleybourne! I loved the game until the fortress defense. I have slogged through 7 stages of it, and, having taken a break from it, I'm not sure that I will finish it.
It was bad enough at first when it was just one fortress per stage, but then it started being two and I just lost the will to keep doing the same thing over and over and over. I think I stopped at Stage 7 like you. I am very unlikely to go back to it either, which is a shame because the rest of the game was fun.