There is a too long, didn't read right at the bottom. Some minor spoilers written in character.
Yes, I am biased. Trinity Seven is one of my top 5 favourite series. I have read the manga (to the latest translations) and seen the anime.
Story: 6/10
It features a different character altogether. The concept is there, but man, it's way too short. 55 minutes is a slap in a face when it's called a movie. The first 5 minutes are a recap, the credits run for like 4 minutes and the ending part half a minute. The ending implies there's more to come, so I won't touch on it much. Read the manga if you want to know what's probably coming next. Anyway, story is same old same old. Pretty predictable. I'd say 30% of the whole "movie" is the fight scene, which is really short. Then again, I've never read this part of the story before in the manga, so I have no idea where the source is from.
Art: 10/10
The anime was somewhat ok, but that was kind of expected, given the manga is still young (only 60 something chapters so far, translated) but they stepped it up in the movie. The art style similarly resembles KyoAni except the eyes. Everything flows really smoothly, the transitions from serious to relaxing is greatly appreciated. Nothing to complain here.
Sound: 10/10
Hm, I did not expect that soundtracks like what they chose would fit in really well. The background music when connecting to their respective archives also make it seem all huzzah and epic. Excellent choices by the animators.
Character: 9/10
Continuation in each person's behaviour. The MC could have been lewder, IMO. Regarding the new character, the character is portaryed and designed according to their background, so no issues there. Voice on point, state of mind on point.
SPOILERS: The WDL could have had more backstory to him but that's fine I guess. Hopefully we learn more in the coming chapters, scenes and movies.
Enjoyment: 8/10
Very little action scenes, that's all I bitch about. I mean, if you are following Trinity Seven, you would definitely enjoy this. For you newcomers, who doesn't like a nice supernatural ecchi harem with a solid story (read the manga), girls for all kinds of tastes and an MC with some actual balls?
Overall: 8/10
I think this is quite high but then again I'm super biased. I am still salty about the length and lack of depth to the story. It definitely did not live up to it's hype, but at least we know there's more to come and it's not dying out like Keijoo (FeelsFuckingBadMan)
TL:DR;
Ecchi harem movie with a simple plot and short screen time. Fanservice and nostalgia galore. If you've never heard of Trinity Seven, the first five minutes has you covered. Good choice if you don't know what to watch while you eat or if you're just entering the beautiful world of "ecchi harem".