I just finished my first week of GST...and felt so excited to share my experience! Although there are already plenty of similar topics here, I would like to express my thanks for GB. 
I embark my GST journey with GB. I set my progression step to the absolute beginner (PE1, step 1 for all), despite having a few years of weight training and yoga up my sleeves. My weekly program is comprised of 2x(F1), 2x(H1), and 1xMS.
After I have completed my first week, the programs make me realize my weaknesses, especially parts where recurring injuries are present. The strength moves are relatively easy but the mobility moves done in interim are surprisingly challenging...which includes the notorious Swivel Hips, of course.
I am breezing through handstand course right now, but the working capacity would soon catch up to me. I'm sure I won't be clicking more Too Easy very soon. lol
As for the stretch series, I'd like to say that the earlier you do them, the faster you'd be able to correct your imbalances! The stretch series not only concerns about attaining greater range of flexibility but also joint stability. It sounds weird, I know. But it just cured my posterior ankle impingement after just ONE Middle Split follow-along. I've had this for weeks and couldn't do anything about it. :/ Now I'm completely pain-free.
So thank you very much, GymnasticBodies. I'll continue to practice GST with a mindset of a journeyman. I also look forward to add Front Split and Thoracic Bridge in January 2017 as well, once my chronic pulled hamstrings get better with isometrics I currently do on top of GB.
NT