Ages ago, the goddess Athena was served by fighters called Saints who channeled the power of the Cosmos within them. Now a youth named Seiya has trained to become a Saint himself by earning the mystical Cloth of Pegasus. He is joined by other Saints with Cloths of their own to fight for Athena.
Note: Chapter count includes an omake story "The Swan's Tale: Natassja of the Lands of Ice".
Saint Seiya was published in English by VIZ Media as Knights of the Zodiac from January 21, 2004 to February 2, 2010. It has also been published in French, Italian, Spanish, German, Portuguese, and Chinese.
Saint Seiya is a shounen manga that has many good starting ideas and lots of potential. However, it has numerous problems that prevent it from realizing that potential to become something great.
-- THE PROS --
The Cloth armors that the Saints wear (especially the Gold Cloths and Divine Cloths), by and large, are pretty cool looking. You may find yourself wishing you had a badass looking armor to wear every time you fight someone. In addition, this manga features a wide variety of nifty superpowers and abilities including: destruction of atoms, absolute zero attacks, illusions, telekinesis, barriers, energy blasts, mental assaults, hand to hand combat, fighting at the speed of light, and much more. Of all the special attacks that the Gold Saints wield, Galaxian Explosion and Lightning Plasma are my two favorite finishing moves.
There are lots of characters in this manga: The Olympian Gods, the Saints, the Mariners, and the Specters. For myself, I am partial to Ikki, Hyoga, and Aiolia simply because they each have their moments of badassery as they show off their skills to wipe the floor with their opponents.
-- THE CONS --
First off, there are very few female characters in this manga. The ones that are present are relatively weak and largely irrelevant in every arc of the manga. So don't count on any of the twelve Gold Saints to be female. They are all men, a few of which are pretty boys, which makes for a yaoi baiting sausage fest of sorts. Athena, being an Olympian Goddess, is supposed to be extremely powerful given her tremendous Cosmos, yet the manga makes her out to be mostly helpless and pathetic. She always needs her Saints to rescue her. I have no idea why this manga insists on not having any competent and relevant female characters.
Second, without spoiling anything, it should still be noted that many of the battles in Saint Seiya are full of asspull victories. The characters will be in fights that they have no reasonable chances of winning, given the difference in raw combat stats between them and their opponents. So do they use clever tactics, strategy, and deceit to win? Well, no, they never do that. Do they get their asses handed to them, leave, train, and then return once they can hold their own? Well, no, they don't do that either. So what do they do, you ask? It's simple: They burn their Cosmos to match or exceed the power of their foe to defeat them. Seriously, almost all the fights follow this format: the enemy is too strong and is kicking the hero's ass, time for him to just burn his Cosmos and somehow overcome this challenge due to sheer love of friends/justice/duty. This is ludicrous because it allows the characters to be as strong or weak as the plot demands at that point and time, coherency be damned. This creates a sense of faux-drama and fake hype for enemies that we know are too strong, but in reality are going to lose not to superior wit and intelligence, but due to the mangaka's incredibly lazy writing.
-- CONCLUSION --
Saint Seiya is something that is good in theory, but is poorly executed, resulting in a mediocre reading experience. The manga is creative with Greek mythology, has a few characters with moments of badassery, and some nice superpowered attacks. But it is full of tropes and cliches that anyone not new to anime and manga has seen in shounen series billions of times already. The manga's cast of characters are relatively shallow and lack any interesting quirks, and it doesn't help that almost all of them are male to the exclusion of females. Though perhaps most damning of all: the fights are constantly full of asspulls/inconsistencies, which is extremely anticlimactic and is just a slap in the face of the reader who is expecting something at least somewhat credible.
Overall, I wouldn't say that Saint Seiya is a terrible series (I've seen FAR worse), but if you are looking for a quality shounen series to read, I strongly suggest looking elsewhere.