The motivation for Thanos is literally a teenage-themed guy-wants-to-impress-girl. Maybe this appealed to the primarily male, teenage audience in the early 1990s or maybe rejection by the girl was the limit of existential dread immediately following the end of the Cold War. There isn't much drama because we're repeatedly reminded how invincible Thanos has become followed by one scene after another of Thanos demonstrating invincibility in the face of increasingly powerful forces. Any advantage the united forces against Thanos possess is granted because Thanos deliberately weakens himself to make the event more challenging and (again) impress the girl.

Spoiler

The only reason Thanos loses the gauntlet is because, according to Adam Warlock, he didn't believe he deserved to have it anyway. So the defeat of Thanos was inevitable.

The lead-in to the big battle is interesting. We see Thanos wipe out half the population of the Universe, leaving humanity in particular shaken and horrified because they have no idea what precluded the event. We see a brief struggle for power over who will lead the counterattack. We see the inkling of a masterful plan by Adam Warlock through his insistence that he requires the participation of certain players (though this is thunderously anticlimactic because no one really plays a significant role).

The battle itself is repetitive. The aftermath is... well, it certainly doesn't resolve the problem of there being a single entity with the power to destroy the universe with a snap of its fingers. That power just changes hands and we're expected to trust it. Ehhhhhhh. No. Destroy the Gauntlet and disperse the stones, folks.

If you want to read this for a portion of the source material, jump right in. If you're looking for a bit more drama and character development that doesn't lean on 40 years of preceding comic books, go see the movie.