Gods, men, and everything in between clash in Guardian of the Galaxy vol 2

*SPOILER ALERT*

Sequels to movies are almost never better to the original. The writers, directors, and editors try to take what people liked abut a film then amplify those elements while toning down whatever theme or element the fans were indifferent about and didn't like. The problem with this procedure is sequels tend to lose its balance and what made it good is no longer dictated by the artist but by the fans. Guardians of the Galaxy definitely did amplify elements that the fans like (such as how adorable Groot is or how intentionally unintentionally humorous Drax's lines are) without taking away the epic adventure of the story line or the relatability and realistic nature of every character. Star Lord was still a huge nerd, Rocket still continued being an asshole who is too smart for his own good, Gamora still stayed shrouded in mystery.

The biggest change to the story was the addition of three new characters who were origional to the comics, this includes Ego (a sort of god and Star Lords father) and Mantis (a psychic who works under ego.) You discover that Ego has been looking for his son for many years due to the fact that Star Lord is the only living individual with the celestial powers that ego discovered in himself. This is why Star Lord was able to hold an infinity stone in his hand in the first movie without being obliterated. Things seem hunky dory until you find that Ego is actually a sadistic maniac who has killed all of his other children who do not hold the same powers as he does, and with the help of Star Lord he intends to destroy the Universe.

I mean what are you expecting, its a Marvel movie, there's no plot without an impending apocalypse.

We are not likely to see the Guardians of the Galaxy until the cross over with the Avengers in Infinity War where the infinity stones will become even more central to the story.