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: Dennou Coil
Audience-Alienating Premise: This is a likely reason for this series never getting licensed by a foreign publisher. The cute art style and young age of the cast seem to target children, but as the series goes on it starts touching on the sort of transhumanism- and internet-related philosophical questions that appear in series like Ghost in the Shell. Now, you could maybe tap a certain market with childhood nostalgia clashing with such difficult topics, but the maturity of the story is also undermined by the persistence of soft sci-fi and "magical" tropes, especially the ending.
Paranoia Fuel: Augmented reality works by processing input from cameras and other sensors to insert images of things that aren't really there. The glasses could well have sensors in them, which explains how it works when their pets are in front of them, but we regularly see the pets moving about where no one is looking, and they can observe and react to events that no glasses-wearing human was watching. They're used to spy on other glasses-wearers, as well, and they seem to do this just by looking at their quarry. So there must be sensors all over the place... even on private property, because the pets can walk around your home while you're not looking. Satchii is polite enough to ignore this, but a bunch of script kiddies have learned how to make their pets use those sensors to track your every move.
For the cyberbody separation of the Coil phenomenon to work there must be a constant overlay of the digital body on top of the real one when looking at someone through the glasses (same with making someone invisible - the glasses don't just add digital information they are replacing everything you see). When Daichi first discovers his "beard" (which is only visible through the glasses) he is naked in the bathroom. For this to work there must be a server first capturing then rendering his naked body.
Puppy Love: The kids and their puppy love is so cute!
Fumie tends to disagree.
Tear Jerker: The three-episode-or-so-long endgame is just loaded with them.
The end of episode 13 also counts.
Ugly Cute: Densuke, Oyaji, and probably even Satchii.
Villain Decay: Satchii starts out as something of an Implacable Man and gradually becomes less and less of a threat with the appearance of Isako and more advanced illegals, being eventually abandoned for a less-friendly mk. II version.