Note: I went to see the movie in a Japanese cinema, the version most likely slightly differs from the net/DVD version.

Definitely can't say I liked this more that the TV series. The movie doesn't have much of what I was eager to know after the two seasons - no character backstories and surprisingly little communication about Hira and Kiyoi's relationship status. I was expecting some more development of this topic after S2. First thought it might be because of the focus on the character's feelings, but that wasn't the case either, unfortunately. There are so many things happening at once plot-wise that the production probably found it hard to emotionally stress everything properly. A little disappointing overall, but definitely not boring to watch.
I liked that there's more focus on Kiyoi's personality and feelings, but was a bit upset we didn't get to hear his thoughts like in S2. Also REALLY happy that he's not toxic anymore and focuses on proper communication (which obviosuly wasn't the case before).
Hira's character development: good. The strong supporting characters: amazing. I really enjoyed the photographer man and Anna's influence on the plot. The story was well-paced, but could be a bit more thrilling. But this franchise generally lacks powerful culminations, so it's not too noticeable.
Overall, very enjoyable! The cinematography in the movie was much more high-quality than in the series, now it's not only Kiyoi, but every third shot that you can feast your eyes on. Very easy and pleasant to watch, nice weekend movie. And obviously, if you enjoyed the series, this is a must-watch to calm your heart and observe that character development we've been waiting for for a whole two seasons.