The first two episodes are strong, with lots of unexpected twists and a story build-up that promises a wacky comedy-adventure featuring a cast of quirky, unique characters going on quests and exploring this fantasy world while searching for a way to defeat the evil Demon King. Unfortunately, all plot gets side-barred in the name of endless wish-fulfillment fanservice and obvious jokes that try to convince you they're self-aware and deconstructive by being transparently self-indulgent.
Kazuma checks off all the boxes of a self-insert main character: apathetic, plain, otaku, social recluse, smarter than average, inexplicably never romantically interested in anyone, and completely essential to the survival of a bunch of powerful girls. He accumulates the usual harem, each with her own quirk that usually manifests as a fetish and who views Kazuma as her leader for no particular reason. They are all walking the edge between living-stereotype and actual-person, with 90% of their behavior conforming to a single gimmick and small slices of personality and motivation.
The characters show flashes of personality and life, when they aren't constantly reinforcing their identities as "girl who always does that one stupid thing", and the clashing personalities occasionally make for some great humor. KonoSuba tries to stay self-aware and subvert all the cliches of the shonen-harem-videogame-anime, but it lacks the self-respect to not dump minutes worth of pointless fanservice into every episode while playing the exact same jokes over and over again. It feels just like every other trashy harem anime, instead of the parody of one that it's supposed to be. Rather than being a story about strong characters growing together as a group, developing themselves and exploring their world in true JRPG style, all the while bouncing personalities off each other's and poking fun at videogame tropes, most of the screen time is devoted to showing off insecure girls embarrassing themselves in front of Kazuma and inevitably begging him for help.
There's a distinct lack of detail that destroys all credibility of the premise. Concepts are constantly brought up and never expanded on, power-levels and abilities are completely arbitrary and inconsistent, random factions and countries are brought in and out of existence for plot-convenience, no one has a backstory, and nothing external to the plot of each episode ever happens. Every quest is stand-alone and insignificant, and the characters never change at all or improve their relationships in the slightest. None of the characters seem to even speak to anyone but Kazuma after they are introduced, unless they are talking about Kazuma, and they don't have any sense of familiarity with one another at all.
There are a dozen better comedy ecchi shows that have everything KonoSuba has, plus realistic relationships and some level of progression throughout the series, and - frankly - better fanservice. There are some good jokes and cute moments sprinkled throughout, but they aren't worth the 10-episode slog of the same harem garbage from every bad anime over and over again. Good voice acting though
