Clart,
I did TWFH for two winter seasons quite early on in my climbing life when access to a wall was hard to come by but had good access to a proper weights gym.
My thoughts from the top of my head (for what theyre worth):
1. Alot of pain - 30reps is insane burn.
2. Really dead tired, aching body after the sessions (eg. lifting a key to unlock a door was tough!)
3. I was a bit used to weights before i started but it still took me a long time to dial into the first phase.
4. I did arms and shoulders Mon and Wed and Tits and back on tue and Friday meaning i could kinda struggle through a climb at the weekend with some sort of pride.
5. Doesn't do abs, or other 'core' things like thighs so muscle mass gains are minimal. did some aerobic work on most days - get the blood going etc.
Gains
1. Max strength or power not improved that much (first time I did it)
2. Endurance went through the roof to a manic level!
3. Second time round I extended the strength phase at the end slightly and binned the 'bring it all together' phase.
4. Would recomend it, especially if you've not done weights before but would target strength more - especially for bouldering