[TW: There are no trigger warnings for this series! :) ]
I don't have evidence for this claim, but I feel as if series centering around sibling relationships where the sister character is actually a huge nerd are becoming increasingly popular and more numerous these days. I can think of two other series [Oreimo and Watamote] off the top of my head who have a similar theme to Himouto! Umaru-chan. Despite this, I feel as if Himouto does the best job at tackling this theme. It's simple slice-of-life with the only real difference being that Uramu tries to keep nerd side somewhat secret from all her friends. It's not overly romantic nor does it have any incest themes like Oreimo, and it is actually easy to watch without painful secondhand embarrassment like Watamote. So for that, I am really thankful.
Even then, the mangaka does a splendid job at conveying the characters' relationships with one another, whether it is siblings or friends, you can really relate to them and probably are reminded of your own relationships in life when reading. Also, the mangaka's main strength in my opinion is being able to convey a sense of nostalgia through simple tasks, whether it be a meal with others, or the passing of the seasons.
There's nothing wrong with the art in this series, there's just nothing really noteworthy about it either. It's fairly forgettable, but the relaxed style does fit the theme of the series very well.
I love the female characters in this series, like a lot. They aren't bland copy and paste manga archetypes that you can find in essentially every series, they're unique and are able to stand by themselves. Each female character gets a decent amount of character development and screen time, and in addition has a unique little quirk to her that makes her so endearing to the reader. I honestly can't pick a favorite, I love each of them so much, for different reasons.
Also, Umaru is totally the perfect example of any girl who is into anime/manga. Even if you aren't a girl you will totally relate to her habits and antics, I promise.
I really like this series. I'm not sure I will keep up with it every week since it is published weekly, but it was extremely enjoyable to read it and I will be following the anime. I will complain that I feel as if the story kinda stagnates in some spots and it takes an extremely long time for any plot progress. But that's not the really aim for this genre so I can't really fault them too much I suppose. Near the end of my reading it did get a bit tedious, though presumably that wouldn't happen if you read all 100+ chapters in one sitting.
Would I read it again? Maybe. Would I recommend it to others? Oh yes. It's relatable on essentially every level, from the sibling relationships, to the nerdy side of Umaru, and the antics she gets up to with friends. It's great. A wonderful series that you can read without worrying that someone is going to die.