If I was reviewing this purely based on my experience I'd give this 2 stars. I'm not a Steven Universe fan, I know very little about it, but the dev seems to assume you've watched all episodes. You may say this is reasonable, and mostly I'd agree. However, for players who are not familiar, there is no real explanation of who characters are, you get name drops of characters/events that probably occur in the TV series but are not explained in game, etc. It's a pretty bad experience.
The reason I'm mentioning is 1) to clarify my stance and 2) to point out that this doesn't have to be the case. There are plenty of games on this site based on existing IP's (Danny Fantom, Avatar, Naruto, Ben 10, etc) that I have had little-to-no background info about but have still been able to follow along and enjoy. In fact, I thoroughly enjoyed Jikage Rising (Naruto) and this caused me to go watch the anime.
However, ignoring this and pretending that I know everything about the SU universe, it's still just an okay game. The art is very true to the series which is a plus (sometimes, but other times it is a minus as there are some fairly unattractive characters in the show...), and sex scenes are animated, but the game play is poor and dialog is average to poor (many grammatical errors and relatively basic dialog). The dialog alone doesn't really give you the info you need to know what to do in order to progress. Often times the hints in the phone can help, but often times they do fuck all (ex: tip is "level up Jenny" - how the fuck do I do that???).
I'm giving this 3 stars in order to account for my ignorance on the IP. If you're ignorant about the IP, I'd say it's 2 stars.