I really love Spark. I've found a ton of good things about it, and even some bad. The list of bad is a short list. So here it goes:
If I take it before an evenning workout I can't get to sleep until late. I'm talking really late. 3-4 am kind of late. I have to wake up at 3:30 am for my new job. That sucks. Now that I'm not using it for evenning workouts I've found the other negative thing about Spark. I've become accustomed to having the amazing workouts that Spark provides. When I don't use it I struggle to get through the workouts. Trying to workout without Spark after being used to it is probably what Superman feels like when he's exposed to Kripronite.