Black Summoner takes a lot of the good characteristics you'd find in several different standard isekai and puts them all into one show. You've got a pretty well rounded MC who's just OP enough to be likeable but not so OP that it's obnoxious. You've got a great cast of side characters who are actually "Characters" with thoughts/feelings/motivations, and not just a harem of girls who love the MC for no reason other than him existing, and you've got a good amount of action that's actually nice to look at. The plot is kind of slice-of-life / action where things are happening and progressing but things are also taking their time. So by EP 5, which is where I'm at, you're only starting to get a hint of what the overarching plot might be, but the story keeps you fully engaged.
The show does kind of gloss over the magic/skill system and how he and his comrades power up / rank up, etc. but it's done in a way that doesn't make you feel lost. You know just enough about what's going on with his skills/powers to enjoy the battles, but you don't get tedious info-dumps / lectures on the skill/magic lore.
Don't get me wrong, this isn't a masterpiece by any stretch, but it is what it's supposed to be, isekai/fantasy wish-fullfilment, turn-your-brain-off, fun. It does that right and is definitely worth a watch. All-in-all, it's a pretty chill, medium-stakes anime that doesn't take itself too seriously but isn't silly. It really hits that nice sweet spot of enjoyment. Don't watch if you don't already enjoy kinda-trashy isekai anime. Episode 1 is a little rough though, you need to get to episode 2 before things really settle into a grove.