Ok, an Isekai that actually explores the world and its people, an OP MC that still uses tactics and strategy instead of bull-rushing everything, interesting side characters that make interesting stories (I mean, the maid and the sailor story was fantastic and this Mario one was incredible) and an acknowledgement that maybe Japan isn't the only country being Isekai-ed...
Add to that the incredible Art level and the loveable MC that doesn't actually hate his past life.
Damn I love this manga.