First things first, Nichijou is a comedy first and foremost. While there is a bit of a slowly paced overarching storyline regarding the relationship between the two main groups of characters' (Mio/Mai/Yuko and Nano/Hakase/Sakamoto) the series priority is to tell jokes. One thing that I think really makes Nichijou stand out is its sense of continuity, which combined with the series wide variety of humor creates a show full of running jokes that create a foundation and then build off of it. The comedy is layered in a way where a lot of jokes function both as their own payoffs and buildup to other jokes in later episodes. The voice acting and animation really bring Nichijou's over-the-top sense of humor to life. Earlier episodes consist of a number of small segments, while later episodes seem to contain more long-form scenes (which makes sense, as the two factions of main characters meet each other in the second half of the show)
I also really enjoyed the series ending. Nichijou ended at the perfect time in my opinion. It gave closure to the main story points. Nano's character arc is complete, the main characters have become close friends, and Mio's determined to still do her best to ask out her crush. There are some things that didn't receive closure, but it really isn't that big of a deal. Nichijou, as a comedy , was never really supposed to be a story driven show. The comedy reaches a nice climax and the main characters' relationships receive closure, which is what's important.
