It looks like that study measured power as well. As for anecdotal/user feedback, I think it's a solid ingredient. I found it helped with my endurance while lifting, allowing me to not really feel quite as "winded" or tired between sets with short sets and/or demanding supersets. It also seemed to sometimes encourage me to take shorter rest periods as well. Now, I did not notice anywhere near a 20% increase in bench press 1-RM in 7 days (i.e. not 300 to 360), that'd be insane. I also don't really think I noted a 20% increase in reps on my first/main/strongest set within a week either (i.e. 10 to 12 reps at a given weight). What I do think it helped with pretty early on is endurance during later sets in the workout, where adding a rep or two here or there is very possible due to the increased endurance. I also think it helped with the limited actual cardio I do haha.
It's a solid ingredient IMO. It's not exactly cheap as a standalone (I think it's normally like $20/month), and it doesn't exactly taste good alone, but when mixed in a flavored supplement it's no big deal IMO. As for if it's worth the price, that's a personal decision, and I think it really depends on your training style. If you play sports or do something like crossfit, then I think it'd be great. If you do heavy powerlifting, maybe not so much, but if you like short rest periods and/or super/giant sets, it may be worth a try.