Boku wa Imouto ni Koi wo Suru tries a lot to be a serious story, which is likely the main appeal for most people who seek this out as a romance, but it often feels like an embarrassing fever dream. Its theme is hard to tackle with, and it's even harder to do it justice (considering it's such a sensitive topic). Instead of a deep, genuine emotion, it ends up being very superficial and down to sexual attraction.

I found it hard to really connect with the characters considering how generic they can be, with barely any decent backstory to give you time to get to understand them or to justify the origins of the feelings for each other, they don't stand out at all for the viewer and they change their attitude and personality wildly as the plot needs it; this in turn makes some scenes comical due to how contradictory their actions can be. Yori's sudden interest in his sister comes out of nowhere and just the same with his sister, like the writer just pushed a button to rewire their brains so the story could happen. His behavior is rather offensive considering he's practically forcing himself on her in several scenes, something I don't think she'd appreciate it if her character wasn't so inconsistent. It doesn't actually feel like she's any interested in him until he makes this apparent, so that's a thing.

The dialogue can be pretty dramatic and cheesy, it is on par with what you'd expect from a parodied Shakespeare tragedy in the background of a movie scene. It all comes down to a forbidden love being discovered and shunned by others, going as far as having religion as a moral or social obstacle for their relationship, one they have to overcome somehow.

The art and sound are pretty neat, however, although it can be considered "generic" as well for some since it reflects a lot of the aesthetics of the time it was made, as well as its genre.

For what is usually said about themes of incest in anime, works seeking to actually portray that in a serious way are extremely rare, and works that do achieve that are even rarer (not that I know of any). I imagine anyone looking for a romance wouldn't have this as an option due to the theme of incest, but for those who are actually looking for the incest aspect of a romance anime, it is hard to say it is worth a shot. You will likely find better content in amateur writing uploaded online.

PS. The review system from this site is quite problematic and annoying. This is what I have to say about this short OVA, what else does the staff want me to pad it with to reach mysterious quotas of characters and alphanumeric ones? Next thing you know I'll be writing a novel as a review.