I wouldn't call myself a huge fan of relationship comedy anime outside of a few exceptional examples (for me, those would be Nodame Cantabile's first season and Maison Ikkoku) but I did thoroughly enjoy this OVA. The jokes hit the mark more often than they don't and the way in which it mixes a mock-serious sci-fi story with a bunch of very silly subplots is what makes it stand out.
To begin with, the plot. It's a somewhat standard "hopeless boy surrounded by diverse girls embodying different fantasies" comedy on the surface, although the girls are a more interesting bunch than "cute one, tsundere, sister figure etc" by virtue of also being parodies of sci-fi anime archetypes; alien princess, super-strong killing machine, child genius, futuristic special forces. On top of that there are a series of events that make up a sci-fi plotline of their own which is reminiscent of other light-hearted adventure shows like Outlaw Star.
As a whole, it's enjoyable and offers a nice twist on the usual harem comedy.
The art design is very 90s. The characters are drawn in a style that screams Outlaw Star, which is quite fitting for the sci-fi styling. While it could be considered functional and unremarkable, it is nevertheless fun and, to my mind, distinctive. You wouldn't want the curvy and emotive characters of a Takahashi comedy show, or a hard-line Dynamic Pro style full of facial hair and giant melons, for a show which at its heart is a love letter to 90s sci-fi anime.
Sound is unremarkable but impossible to complain about - the dub voice acting ranges from quite bad to very funny, and the "Ayeka laugh" is pretty iconic as THE female villain laugh. It's a show of caricatures, and so exaggerated voices are ideal.
The characters are all funny and well-developed for what could easily have been one-note jokes, setting the show apart from the competition. Mihoshi manages to quite nicely be a comic homage to characters from Bubblegum Crisis, Outlaw Star and other shows, as an example.
In terms of pure fun factor, you can't beat this OVA. It's a far above average example of a genre that is crowded with unremarkable entries.