I'm not a huge fan of Iseleve, but I found enjoyment in it. For me it was a bit like watching a campy movie for fun, part of the fun was very much jeering at it with others. Everything is so over the top and absolutely ridiculous. Some parts are bananas, but not once does the show acknowledge its ridiculousness -- it plays everything completely straight faced. It made me wonder: was it written this way because the author thought this Mary Sue would be super cool, or was it written this way because the author wanted to absolutely abuse a few tropes to the furthest extent that he possibly can. I don't know what the truth is, it may be a mixed bag, either way the end product is fascinating to watch.
To enjoy the show, I think you probably also have to enjoy the Mary Sue & wish-fulfillment aspect to some extent. There's just too much of it to ignore or jeer at all of it.
I think what I don’t like is that is feels like the MC is literally handed everything and there is no challenge whatsoever; for me it feels a bit like a story-on-rails feeling and I don’t feel really connected to any of the characters, as if they are just cookie-cutter templates with no depth or personality.
Absolutely, this show has little nuance. The characters don't feel like real people. The plot and character development is asinine. The visuals were actually OK, there were a few pretty scenes.
I think the top review on MAL is worth a read if you haven't read it yet https://myanimelist.net/reviews.php?id=490093 ... Though be warned, that review may be more interesting than the show itself.