My laptop has an I7-8565u and it is pretty mediocre on performance. Power consumption wise fairs better... Light use gets me 8-9 hours on battery.
The performance drop on this CPU under a constant load is dramatic... For example, I'm getting 730 cb on my first run of Cinebench R15(close to the 7700hq), but after 3-4 runs I'm dropping to 560 cb, which is mediocre at best. When the CPU it's colder I'm reaching 3 GHz+ all core turbo on it, but when it gets hot I'm averaging 1.9 -2 GHz all core. Even though this is a U processor when it's going to its max turbo frequency it draws 56W(well over the advertised 15W tdp - that's maybe true at 1.8 GHZ)... so it's pretty close to the 7700hq in terms of power consumption when it is going at...