These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Yokohama Kaidashi Kikou
Crowning Moment of Heartwarming: Several (practically the whole series), but the scene with the underwater streetlights deserves special mention, as well as Alpha's last chapters with Takahiro.
Fridge Brilliance: Alpha's owner sends her a present together with a coded message which must needs be delivered by a robot. In hindsight, this is obviously a ploy to make Alpha meet other androids, make new friends and come out of her isolation.
Those all-female androids? They transfer data to each other by pressing their tongues together. Believe it or not, though, this actually makes a fair bit of sense in context.
Carried to an extreme by the relationship between Maruko and Kokone, though; see Green-Eyed Monster above.
Mary Sue: Ultimately averted by Alpha, although in the early chapters her portrayal can be interpreted as having Sue-ish qualities.