Gunbuster should be watched simply because it is one of the best animes of all time. It's worth noting that it is the directorial debut of GAINAX director Hideaki Anno. Yes, he handled The Wings of Honneamise as an animation director, but this is his first as a full fledged director. At least, I'm pretty sure.
Also, Gunbuster is where the "Gainax Bounce" originates.
And there are boobs in every episode, or nearly so. So even if you're just in it for the tits, it's worth watching the whole thing (the scene in the bath gives you a better view, and of all three girls, anyway).
Should be 80s no? Since at least the show aired in '88. Unless, the poster or setting is the 1970s specifically.
I think it's supposed to be in a speculative SF future, but it looks very 80's (which makes sense based on when it was done), in this future, the USSR never broke up and provides a major character.
