TL;DR: Trademark relaxing "healing" as expected of the franchise, small hints of the end of the story between the four girls. Works well as a recap or refresh episode after "More Aggressive".
If new to this series, I recommend watching the OVA and two TV seasons before starting this - however, this movie works as an introductory piece as well.
Story: It actually feels much like an extended normal episode of Tamayura, and the longer airtime led to substantially more and higher-quality scenes and interactions between the cast. The relationships between the four main characters and the supporting cast remain the same as ever. It definitely has not lost the trademark healing feeling.
Art: What an amazing jump in quality! I was particularly surprised and impressed by the difference in the character designs, but every visual aspect has shown some improvement as well. That said, the gentle backgrounds and colors seen in the past "Tamayura" works has remained, which only serve to immerse the viewer in a gentle mood.
Sound: Spot-on sound as expected of the franchise. Satou has a great knack at sound direction in both Aria and Tamayura, and it shows. The voice actors remain vibrant and gentle, and their familiarity with the characters shows in their delivery.
Character: Although far from unique, the four main characters interact with each other brilliantly as always. None of the characters seem out of place or lack airtime. The supporting cast holds the main characters up as well, and they do not seem discarded or forgotten. It has been like this since the very beginning, and it's great that this has not been lost even with the amount of character development every main and some regular supporting characters have undergone.
Enjoyment: Trademark "healing" anime feeling, an incredibly refreshing watch after a long day. The extended time only adds space for the producers to fill in the atmosphere and further immerse the viewer in a relaxing, warm, gentle feeling that has been this series' strong point for its entire run.
Overall/Remarks: Fans of "Aria" and "Tamayura" cannot be disappointed with this great addition to "healing" anime, and it can only get better from here!