As of writing this there has currently been 6 aired episodes.
I was really looking forward to Marvel's Guardians of the Galaxy after seeing the shorts about the characters' backgrounds, but unfortunately the actual show left much to be desired.
Let me just start with saying I'm a big fan of the Guardians of the Galaxy comic books, and I am very familiar with many of the characters introduced in the show.
When the show started I immediately felt that this show would be just based off of the characters, with no connection to the story lines of the comic books - which I'm completely fine with - but I still feel like the show needs to honor it's source material.
The show is also supposed to be a continuation of the movie (while still not being part of the Marvel Cinematic Universe) but it's so sloppy compared to the movie. The soundtracks aren't as well placed as they were in the movie, the characters are slightly dull and shallow and the story lines are mediocre most of the time.
Spoilers ahead: The show started reasonably strong. You could tell from the jokes, the dialogue and the slightly forced moral-of-the-story that this was a show for kids and would probably not be enjoyed by most of the more mature audience, but I still enjoyed it; I take every chance I can get to see my favorite comic book characters move and talk on a screen.
What really blew it for me however, was the constant introduction of cosmic characters. I have always loved to see cosmic characters in the comic books - Galactus, Thanos, the Collector etc. - and I thought I would love it in the show, but unfortunately it was poorly executed.
These cosmic characters have a reputation of being extremely strong in the comics, but in the show they are nowhere near that level of power. The Black Order (Thanos' generals) consisting of Supergiant, Black Dwarf, Proxima Midnight, Ebony Maw, and Corvus Glaive, were easily matched by the Guardians while in reality they would have beaten the Guardians senseless with ease. The Collector and the Grandmaster were both easily thwarted by the team while they are both supposed to have some of the stronger intellects in the universe. On the plus side though, Drax' power level seems to match his comic book self more than his movie version.
So, to summarize: Pros: You get to see your favorite team in new environments fighting new battles, and if you can tolerate the bad you will find quite some nuggets of gold here and there. That's it, that's the only pro.
Cons: It's not honoring it's source, it's poorly executed most of the times, the characters feels forced and shallow, the morals feels pushed down your throat more often than not and the stories doesn't feel convincing at all.
If I hadn't read any comics I would probably have given this show a 6/10, maybe 7/10 if it caught me on a good day, but as it is now I give it 5/10. Would not recommend.