Before I start this review: This is my first one, so beware.

That said, let's get right into it:

Nozo x Kimi is mainly an ecchi somewhat romantic comedy with a strong emphasize on the ecchi part.
For the inclined viewer of this 3part OVA it means a ton of panty shots, groping, a few nipples and other nice visuals to behold with all the fun little accidents and intentional PLOT accompanying it.

As the source material is the manga written and illustrated by Wakou Honna, the story is based on a similar premise: It's about two individuals revealing each other to themselves by peeping or at least one's reaction to it, which is not unlike her other creation Nozoki Ana.
Yet Nozo x Kimi is overall way more harmless and less dark (in the OVA) as it focuses more on the interpersonal relationship between the mcs Suga and Komine, who interact with people they are more or less interested in. The story mainly lives off the interaction of Kimio and their growing relationship and some running gags, about how much one is a perv and the other a ~~literal closet perv ~~ good hearted boy .

The three OVA-episodes are visually nice regarding coloring and style although it cannot quite convey the facial emotions on which the manga heavily relies due to the shift to an easier to animate style. The animation is not bad (imho) and the voice acting is quite enjoyble while the music is at best unnoticable, in fact don't bother with the ED at all, the song is funny trash and the visuals are only recaps.

Storywise the first two OVAs were pretty much the same as in the manga apart from it choronological order and left me overall very satisfied with the adaption.
Still if it weren't for episode 3 that seemed to miss the tone of the source material by overexerting some character traits (like making a certain character unnecessary meaner or another way more stupid) or completely missinterpreting motivations while at least clogging up the plotholes (by implementing some context scenes out of order or simply inventing new-ones which led to said changes in characterization and tone) accordingly .
Episode 3 is pretty much why this OVA fails to deliver the good points of this manga, which leaves it as a whole only little bit better than a mediocre product that entertains but doesn't really entices one into reading the manga.
Like already said above the story lives off the two main characters, whereas Komine is a rather well-fleshed out character I really enjoyed watching, by reminding me a little of a nicer version of Senjogahara. While Kimio is at least from time to time (disregard most of EP3 he's misrepresented) a good fit and not a complete loser.

TL;DR: Fun ecchi shots, KOMINE, nice visuals, KOMINE , bad music, good VA, KOMINE, good production values a decent adaption which fails to advertise for the manga.