Jump back to 2010-11, around the time this series first came out as a manga. I limited myself to mainly reading shounen harem series, with the usual trinity of action, comedy, and romance. While action was never a must have, the ideal series for me would be capable of shifting between some serious fights/battles to that of silly, romcom shenanigans amongst the characters going about their daily lives. To this day I've grown far beyond this niche, as to now be more enamored toward seinen series that push away from the typical cliches I had normally enjoyed. Sora no Otoshimono, Yuusha ga Shinda!, and Dragons Rioting are some of the exceptions I still currently enjoy (and would recommend), mainly due to their self awareness with cliches and how they choose to handle them for making an entertaining story.
Moving past all this personal babbling of mine, I originally did like Trinity Seven; but as the story's progressed over the years, I find myself at a loss for what exactly has really progressed to begin with. With claudiofd bringing up some good points, I'm not sure how to see the MC as either a hero utilizing evil powers he's stuck with, or some kinda antihero (like from Ichiban Ushiro no Daimaou) that can't help but be a good guy.
The names and explanations of powers are all over the place, and the execution for them is also quite messy to keep track of, with the generic "magical symbols" being utilized constantly. Opponents fought are just as generic, be it disposable fantasy creatures or some bad guy that ends up with Fairy Tail syndrome and joins the cast at the end of the day. Hell,
with the story originally being about the MC wanting to obtain great power to save his childhood friend, it has her being the main villain that also wants to be with him, but can't for reasons X,Y, and Z.
I don't find any of these characters compelling toward whatever they're fighting for, especially with something like death being pretty absent from the overall fights. Tension? Grief? Loss? Nope, you won't be finding any of that here!
(Except for one character's backstory, but hey she got over it pretty fast...)
I also have to bring up how the harem/romance aspect is pretty fucking "meh." While I tend to like seeing true harem endings to stories, I find myself rooting for only one particular character, mainly due to her development as the "ice queen who's heart was melted by the MC's kindness." The fact that she expresses more emotions compared to the rest of the gang has me wanting to see this monogamous relationship happen more than ever, and that's something I've never really wanted out any harem series...
Beyond all my generalized complaints, the bulk of my issues stem from the question I asked above: Is this series worth my time? With pacing so slow and nothing on the line, five or six of years of this series being drawn out has me figuring that it's not even some entertaining series to pass the time with. So overall, "No" is what I'd say toward recommending this.