[no spoilers except general direction]
[not a show to watch for so-bad-it's-good, except the CG jitters]
The main war involves two factions, Green Frontier vs Jesas in Japan. They aren't the only factions, but both are major nuclear waste disposal companies. Jesus operates independently of Japan & causes growing political tension. Due to global warming, land is scarce and their earth cities are mostly submerged.
Start of a few episodes like ep2 & 7 have a clearer recap of events & war politics. The awful tropes in ep1 between the main pilot pair quickly vanish by ep2, after a 1 week training timeskip. There's enough screentime of exploring both factions & it begins rather vague who is the actual 'villain' if there is one. It presents a more human take on war with growing technology & global warming as the setting.
Justice Force, UN & Japan are the other parties. The story, while taking a more unique pov, is unnecessarily complicated by extra parties that aren't well developed and connected. Fortunately they are largely irrelevant, and the conclusion gives closure to various characters, cowards & heroes alike. It's rare for 1-cours to spend such time with non-mc's, while having a real end, as this emphasizes humanity more than just hero fights.
Romance is lite with multiple ships.
There's demon, war, morality themes, but the obvious Christian theme is fairly light.
Art & animation:
CG is 2001 old. Mechs have safe designs, but move like small toys. The mc hero mechs move more naturally & have a bit of weight. CG humans take a lot to get used to, with jittering mocap, weird plastic/metal shading on cloth & hair, ugly mouth & occasional mesh intersections.
Buildings & mech designs don't give any low poly feel. Most have rounded edges with enough details.
But despite its age, it has some attention to detail, like biking in the rain has ripples & faint reflection on the road, or flowing sweat on faces. Eyes have minute motions that attempt at realism, and the soft smooth shadows on faces are much more palatable than the jaggy harsh shadows of cartoon CG like Berserk 2016. Trees in the many forest battles waver to mechs pushing through and strong wind.
Helmet designs blocking much of the face is unfortunate, and with hectic battle sfx, makes it difficult to know who's on screen talking to who. Also GP mechs have a blue-white pattern, while the Jesus pilot suits have a blue-white pattern, causing unneeded confusion.
Video is quite old, but epic orchestral war themes still carry the drama through naturally. Some ambient osts & classy saxophone occasionally fill the politics.
Kazuto: A typical mc with growing AI powers (a rare prediction ability chosen pilots have), finding his own reasons for fighting & taking sides. He and two other male pilots like to travel on roadbikes. They're all normies which give usual romance some potential. Usually he fights terribly & gets injured often, but somehow (plot armor) powers thru. His dad is a mech engineer & there's a fair bit of parental relationship shown.
Kanna: A mostly nonviolent tsundere by ep2, able to talk sense into Kazuto. She is parentless & has an imouto, and travels by rollerblades at times.
Ken: interesting, logical antagonist. His dialogue is full of poetry, with artful flower bouquets behind him. A few gay comments are directed at Kazuto, and apparently liking mechs more than girls/Yu. He wants to develop Kazuto's full AI potential.
Yu: somewhat jealous at Ken's attraction to Kazuto, but she follows rules & is nice even to the enemy.
Side characters: The usual stormtrooper aim skills rain down harmless bullets. This makes many fights boring & frustrating to watch, like a one sided game. War atmosphere & pacing is intense, yet only mc's can hit anything. Many political heads & random characters did nothing for the plot.
Even if you dislike the art or plot, there's at least much (unintentional?) comedy to be found in how faction names are used and character relationships, and the Nana Mizuki song.