FLAVOR. So I take the collagen based on science showing it's good for tendon regeneration. But it doesn't taste great. I've mixed it with many things to offset the flavor, but settled on room temp water as my "favorite". It's not bad that way. I hold my nose and it goes down. But you don't even taste it with Endure X, which has great flavor. You can see the collagen reviews for comments on the collagen.
EFFECTIVE? Yah, stupid effective. I don't want to write this review, because I want the edge over others. But when Coach Eric's automated email kindly asks, well, OK, fine—only for you. Here's the deal: imagine a climbing session where you feel NO FOREARM PUMP. I was cruising up 10s, 11s, and 12s for hours. The only limit was how strong my fingers and muscles were (and how slow my partners were when it was their lead). Having climbed for years and never used anything like this before climbing, I found it to be a wild experience. The drink is not a crazy caffeine shot like many other pre-workouts are, so there's no jitter or crash. It's not like you can't moving as if driven by a motor. Rather it's just that your muscles don't get fatigued and it means you can do a beastly workout. I did find I had an increased need to stay hydrated though. But it was my first time using it, so perhaps it was just higher volumes of rapid climbing rather than the need to hydrate per se. Time will tell. Stellar product.