Good Programm, nice and usable for occasional party djing.
Three things prevent it from being excellent and getting 5 Stars:
1. The most important: still unstable. Getting better with each version, but still occasional crashes, which can be very frustrating during a party
2. Performance is not good. Using a very big library the programms lags when switching between playlists. In addition Disco DJ is using constantly 20-60% of the processor and tops out at 100% when mixing and blending two songs. This is on a Mac Book Pro.
3. Huge Memory consumption. Starting with 200-300 mb and quickly rising with every song you play. I got it to 1.2 GB of physical ram consumption after a 4 hour use which ended in a crash.

Still don't get me wrong, the best DJ software for my needs. And I tried all available on a mac...