Mash-Up #1 End Product

For being the first time I use audacity and the first time making a mash-up I thought my final product was good. The two songs I mixed were "The Riddle" : http://http://www.youtube.com/watch?v=z_q_qytqgcc and "Stamp on the Ground" : http://http://www.youtube.com/watch?v=cHcVU5cGUNE . I thought these songs blended in with each other pretty well. What I really liked about my mash-up was the beginning, the two songs together sounded perfect, you could barely tell they were different songs. Besides that, I liked how the volumes went up and down. You could hear one song louder than the other and then they would switch, but it still sounded good. What I disliked about my mash-up was the middle part, it sounded very caotic. I don't know what I did to make one go way faster than the other one and it made it sound crazy and without any rhythm. After this experience with audacity, i'm pretty sure I can do a much better job mixing up songs.