Gate is propaganda, and based on how high it scores here it's damn effective but as an anime series it fails on the most basic of principles and just isn't any good once you realize it was built solely around being pro-military media fodder.
So let's break this down into the grading criteria itself:
Gate's surprisingly strong opening and base concept is the only reason I didn't rate it any lower as in the right hands they could have been the building blocks for a genuinely good show.
Shortly after the JSDF enters the titular gate things take a turn for the worse and the originally unique and interesting concept of an otaku turned local hero being forced to serve his country in a high fantasy setting who's ruling country had previously attacked Japan turns into generic otaku harem fodder all to sell a 100% pro-militaristic, pro-Japanese message.
Even barring how annoyingly obvious the propaganda is it's a failing in story telling as our main characters stumble through situations that are generally resolved one of two ways:
1. Japan/Pro Japanese characters win because they are 100% good and right all the time (See: Propaganda)
2. The even more annoying: Time skips that show none of the resolution and we are told through literal dialogue breaking the most fundamental of writing rules: Show don't tell.
The plot get's weak quickly, though attempting to add a level of court intrigue and political drama it is mired down in it's inability to make the issues subtle or nuanced as it paints literally every other country, either fictional or real, as bad guys to the bone. Even going so far as casting the US as a country intent on kidnapping members of the main cast for no reason beyond it makes Japan look better by comparison.
Most the world mechanics inside the gate are glossed over or never addressed, there is literally no world building.
The best part of this show by a landslide Gate is undeniably pleasing to look at, the style breaks slightly from the current popular style with the people beyond the gate having a distinct look to them compared to those of modern day Japan.
The people beyond the gate are the most visually interesting though not always in a good way. Their outlines are thicker, instead of clean tonal shading there are shading lines reminiscent of manga and western comics. Their eyes are drawn in a distinctly different style, or at least they are if they are female.
It's the men of the gate who tend to look a lot worse than their female characters.
It should be noted that Itami and his team are not ugly by any means, though design wise the male members of the team while distinguishable from each other are not as interesting as the two girls on his team. That is a running theme throughout the show with the female characters being more interesting visually to appeal to the otaku crowd.
The backgrounds are basic pastel pretty but uninteresting fare, however the Japanese's military equipment is oddly and jarringly gorgeous. Several scenes feature nothing more than military porn, which I have a feeling are the reason the story time skips from time to time, gotta make time for gorgeously animated helicopters, tanks and troops in them.
Pretty basic fare here, nothing is amiss here scene wise but the soundtrack will likely only be decorating the shelves of those who are fanatics for the show it's music is wholly forgettable though the guns are satisfying in their clicking and rattling. The opening song while catchy is nearly identical to that of the second season and indeed anything else that band has produced.
Gate's other biggest failing. Itami is interesting at first but after entering the gate he stagnates and refuses to develop, he never suffers from real struggles and when faced with dilemmas pulls the most stupid solutions out of his ass that just somehow, breaking all logic, work out. His character goes from reluctant hero otaku to idiot wearing a military uniform.
And no one calls him out on his horrible decision making processes.
The girls while cute and basically different from each other are boring at best. There's the quiet and studious but powerful one, the sexually liberated one, the broken but alluring one who will probably end up with Itami if any one member of his harem becomes a steady love interest. That's a creepy trope by the way, and it only gets worse in the second season but that's another discussion for another time.
Oh and who can forget the totally unique and not a prebuilt, no effort required, cliche headstrong, Tsundere, strong in a fight but naive to the real workings of the world princess with (red) pink hair. That was sarcasm by the way, Pina is the most color by the numbers member of the cast and unfortunately the one with the most actual personalty.
Itami's actual military team is forgettable, it's male characters blending together and it's female characters one note characters who are quickly sidelined by Itami's new harem.
Any interesting characters are not part of the main cast and forget so quickly by the narrative that I can't even remember their names despite wishing the show was about them instead because they'd be less boring.
The antagonists are one note, hating on the JSDF simply because it makes for better propaganda and either are killed or humiliated into submission or join the Japanese side for no reason at all.
On the surface this is an okay if not somewhat enjoyable show but once you think about it, Gate fails. It's mindless otaku fodder and if that's what your watching it for then go for it but if you're looking for something less intellectually insulting and with more substance skip this.
The pretty art style and cute girls are a trap.