In terms of pacing, the entire story itself plays itself out at different speeds: there are episodes that seem to rush by in an instant and others that delicately focus on the interactions and relationships between characters. In retrospect, however, no single part ever felt too slow or too fast; rather, the variation in speeds provides a nice contrast to avoid that feeling that you're always on the edge of your seat (although there are no shortage of such moments, so it's not boring either). Unlike a lot of animes, this one actually provides some nice stopping points so that you don't have to binge it all in one go if you don't want to.
The art in Shigatsu can be characterized by thin border lines and bright and cheery colors, which are typical of many shounen/school animes. However, the show later utilizes shadow and subdued colors to portray the more serious and contemplative scenes, which often occur at night or in dimly lit rooms. In terms of art style, the constant contrast between day and night scenes mirror the melodrama of the show, which is quite nice. There is also meticulous attention to detail: every piano and violin scene is animated accurately in terms of hand position, key signature, etc. This is expected from a show that focuses so intently on the piano and violin (and is filled with close-up scenes of them), but there have unfortunately been other shows with similar scenes that tried to get away with simply animating the hands "jumping around" or simply being in a blur.
Being a music-focused show, the producers were prudent not to cut corners on the soundtrack. The music heavily features the piano and strings, and the music that Kousei and/or Kaori perform is often set carefully to the pace of other events occurring in the plot (this technique is most notably seen in Kousei's final performance). Overall, the show utilizes music as a storytelling tool, and the contours of the music closely match the scene unfolding on the screen.
In terms of character design and development, the show features the quintessential characters of a school anime (Kashiwagi and Watari immediately come to mind), although the design that Kousei follows is one that is not often seen. It's not uncommon to see shy children in shounen animes, but to follow one as the main protagonist throughout the series is, in my limited experience, somewhat rare. Most of the characters developed in a natural and expected way as well: Kousei's recovery and change in attitude are the most noticeable, as are the changes in Tsubaki's feelings for Kousei and Watari's outlook towards school and life in general. In that sense, the story could be considered a bildungsroman, especially in Kousei's case.
I must admit that the anime was difficult to enjoy at first due to the long time it took for the entire "main" plot to get started, but I found the subplots and backstory to provide interesting context on the characters, and it provides a nice distraction at times.
In general, Shigatsu wa Kimi no Uso provides an interesting outlook on the purpose and role of music, and expresses it beautifully in a dramatic (possibly too dramatic, or so some people say anyways) way with eye-catching art, captivating music, and tangible characters.
