I played Koikatsu party several months ago, seemed fine. The character creator was pretty good, however the one problem I had was that the main character had to be male; though there is a mod to create a shemale character, basically a female with a dick attached.
The story was meh and the actual gameplay mechanics were meh as well, I don't remember there being much to do outside of the core of the game, I don't remember seeing any mini-games for example. The sex mechanics were alright, but sadly you couldn't go extreme, e.g. piercings, multiple hole penetrations, BDSM etc... it was fairly vanilla stuff + some anal, you could also select different poses. The game does try to add actual character to the characters, e.g. it allows you to select special traits for your waifu, like she has a weak bladder, or she is very well mannered, or is an energetic person, smart, etc... the voice selection seemed decent too. There's also a "storyline" waifu you can pick and customise which comes with a preselection of traits and events that you will have to go through.
In terms of graphics, everything was crap apart from the actual (female) characters. For performance, it was meh; back then I had a 970gtx and had to keep it capped at 40fps so my fans didn't get too loud, but my 970 wasn't the best one when it came to cooling (it was a blower fan, worst type basically).
