When I first opened this I was really frustrated with how the song function worked, then figured out how the pattern mode work realised that it worked better than what I had expected Song mode to want.  Also under the system setting you can (and should) disable the tempo changing with the pattern and also (through this is more to taste) to disable that the drum kits change with the pattern. Very highly recommend that you get two footswitches for it. I have two different kinds of pedals so is visually easy to tell which start/stop and which switches between A to B. If you have a multieffect pedal that takes MIDI CLOCK in, is very cool to set that option and have the Drum machine send tempo controls.  This way with the A/B pedal you can control the tempo synch on pedal. I am using a Line6 M16, which is also awesome, but took me a while to fall for.