Sorry if this Anime Talk's a little late!
Quick summary:
Gargantia on the Verdurous Planet is a 13 episode long anime about Ledo, a young soldier in the Galactic Alliance of Humankind who, while retreating from a battle against the Hideauze, finds himself with his Machine Caliber Chamber on the planet Earth, which has been completely covered by the ocean and humans now live on large groups of ships called fleets. On Earth, Ledo meets and joins up with the fleet Gargantia and slowly gets accustomed to this new way of life.
Probably one of the most noticeable things about this anime is that it is one of those quick ones, being only 13 episodes long. But despite its short length, it does a very good job with establishing the setting early on and exploring some of the nuances of life in this world. Early on it is made clear that while the setting is Earth, it is completely different from what we know as Earth.
Another very noticeable thing about this anime is that it focuses a lot more on characters and setting rather than plot. What plot there is shows up in the second half, with the first half focusing on Ledo integrating himself into the society on the Gargantia.
This anime also does something that isn't often seen in many stories where a person is all of a sudden put into a society that is very different from their own: have a language barrier that has to be overcome. Also, while Ledo is getting used to this new society, he slowly learns the language of the people of Earth and relies less and less on Chamber translating for him.
Unfortunately, the very beginning of this anime can feel a bit disjointed from the rest at first, especially since it is the only scene that takes place in space and is given very little relevance to the story other than getting Ledo and Chamber on Earth until much later near the end. This can cause a little bit of confusion at first, as it gives this impression that there are going to be a lot of battles, even though this is a more slice of life anime.
Overall, in my opinion, this anime's pretty good, even if it suffers from a few pacing problems. It also can serve as a starting point for those who want to see mecha anime, as it does not put too much emphasis on the mecha part.
And by the way guys, I'm sorry if my reviews seem pretty scattered and the like. I haven't written very many reviews, so I'm still a little new to the style. I'd appreciate any advice.