Regarding the harem aspect, there's next to no fan-service so it manages to avoid many of the same harem tropes seen in countless other shows (for example, the "Oh no you tripped and grabbed my boobs/walked in on me while bathing" = scream + slap routine). The slice of life aspect is mostly just their club activities or episodes mostly centered around a few of the girls at a time. Things move pretty slow.
Moving on, the MC isn't a spineless self insert or a pervert either, you can actually understand why these girls are all falling for him. When he decides to drop the chunni bit and act serious, he is insanely good at saying the right things and just happens to keep raising their affection levels. It's entirely possible that he could talk himself into a harem ending without realizing it and getting hogtied by the girls.
For the girls, I found them each to have their own personality and problems and were pretty decently done. Childhood friend gets a special mention just because she has the usual jealousy issue that gets old, but it's flavored by more reasons than just him getting along with another girl.
All that said, this show is by no means perfect. There's really no plot, just something shoehorned into the setting (that probably fit better in the source material) that gets needlessly distracting. Also the show really is all about the girls falling for the MC. Best just to view it as a romcom. Not surprisingly there isn't much of an ending either. Not a cliffhanger, but not any resolutions to the main plot. Personally I wasn't bothered by it since the plot didn't really feel like it fit in this show anyways.
