G Gundam is well known not solely because of being the only Super Robot series in the franchise, but because how ridiculous the story and designs (both bad and good ways) are.
While some bish-bashed the show for being not serious at all compared to the other ones, I would say that's pointless because this story is making a serious show out of a nonsensical story which is so overly serious that it is so godamned fun.
Story: 6 out of 10
Being a Super Robot Anime, you cannot expect some really serious-toned storyboard - It's basically some regular shonen stuff mixed with martial arts that are over-the-top ridiculous and inhuman to start with (say, how the hell do you do the Shoku Hao Denindan where you can spin your whole body and launch like a missile without your head spinning in the process?), you can turn super-saiyan and become golden in colour, a super robot fight to decide who can control the Earth and the colonies...... If you are that kind of people that can't stand bullcrap then it probably isn't a good idea to watch this, but if you simply don't care or doesn't mind then welp.
An American robot that wears a hockey mask, yields its American football shoulder pads and expels its protection chestplate to become a (visually) muscular boxer, and yields a handgun like a cowboy, A Holland Gundam that has a rotating fan on its chest and is basically like a windmill, and a German Robot that looks like a German military officer in WWI somehow performs ninjatsu, and a Sphnix that has a giant Gundam face in place of the human face as it rose. Right.
The characters in the show are just as stereotyped as the Gundams (except probably Schwartz Bruder which is a German ninja), so ridiculous to the point that it's clearly the general image of a certain nation's people, yet so funny that you can't stop giggling at its ridiculousness. Not necessarily a bad thing, as why so serious if the whole storyboard already decided to be not serious at all?
To increase the goofy and fun of the show, the colouring is the good ol' 80's bright and vivid instead of the same gloomy style used in the 90's. This is a reminiscent of the 80's hot-blooded animes to make the scene more hammy that it is.
Sound: 7 out of 10
The OPs (Fly in the Sky and Trust You Forever) are both catchy, and despite the difference in tones, they still work really well with the show.
The BGMs, although they aren't something extremely top-notched, worked and are easily memorised, especially Shining Finger and My Heart is Clear and Serene because you will expect the villain to have their asses kicked really hard by Shining/God(Burning) Finger.
In addition, to emphasis how much Hong Kong martial arts movies influenced the film (which basically actually transformed into something totally irrelevant), several songs have their cantonese counterparts, such as Hoshikuzu no Requiem (Stardust's Requiem).
Character: 7 out of 10
Although it's an extremely generic shonen anime, the characters are well structured according to their own genre, have their own personalities instead of being one-dimensioned, and are all hot-blooded as hell.
The downside is there aren't much stoic persons (or at least logical ones) due to the genre, and Rain doesn't have a really large role in the story despite she should be the hero's girlfriend.
Enjoyment: 10 out of 10
THIS HAND OF MINE IS BURNING RED! IT'S LOUD ROAR IS TELLING ME TO DEFEAT YOU! BURNING FINGER!!!
Seriously, despite most of the sentences are outright stupid, the VAs from both Japanese and English still managed to pull out a straight face, thereby remaining the over-the-top serious hot-bloodness of the show worked so well, even there isn't much content you will still get your emotion flowing because of all that yelling and ridiculous stuff.
See how a person runs faster than a car, uses his cloth to disassemble a Mobile Suit, kicking a whole building straight towards the sky despite being injured, spinning his body without his head spinning, that's the Undefeated of the East for you. Yes, it's that ridiculous, but you can't stop having a big grin on your face even you already saw that coming.
Overall: 8 out of 10
Forget anything related to logic in your head, because G Gundam is a huge throbbing middle shining finger to that in the face. It basically is a representation how illogical stuff can be fun and addicting to watch at.