Here are my experiences using all the different CD and following the recommended instructions on how to use them.
Delta Theta : I listen to this before i go to bed at night. After listening to the CD I will fall asleep within 10 minutes. In the morning I feel alert, not groggy or tired. which is nice.
Alpha: i usually listen to this before breakfast or throughout the day when i am looking to relax. It can almost be like a nap but I don't feel tired at the end of listening to it but rather alert and ready to continue the day.
Beta: i primarily listen to this when I am working and just leave a single track on repeat. It lets me laser in and focus on my work and blocks out the outside world from distracting me. the binaural beats seem to keep me focused while also dampening the sound from around the office. Overall it is a good combination for myself.
Gamma: I sometimes listen to the Gamma instead of the Beta while working or alternate between the two. It is hard to see a lot of differentiation since i am using the two together but it seems to work.
Review on the headphones: these headphones create a very clear crisp sound. I would compare them to others in the $200 price range in this regard, but they do have a softer base sound. I use them for listening to my normal music also, it is a nice feature that they fold up, it makes it easy to fit in the car or laptop case.
I am no expert on this type of product but have tried other binaural beat products before. This Itsu Sync package is just as good or better then others and doesn't require you to buy tons of individual CDs. I like the fact it is straight to the point. It is a really good price also, the headphones alone should cost this much. 5/5 stars