Recently I have watched many movies with:
-depressive endings
-no conclusion (if not small) because most of the time there wasn't anything to conclude
-cruel violence (torture, disgusting and painful deaths...)
-small or not that great action scenes
-lots of really thought out stories with loads of subtleties
So for me, watching 300 is a break from that universe, which is frankly getting way too common and depressive. Instead I get to watch a movie with:
-Tiny plot (less thinking, thats good.

)
-conclusions
-Awesome action scenes with cool slow-mo footage and exagerations
-Mindless violence (in the sense of "I cut you, now you dead, me go cut next soldier)
It was fun to relax from all those other movies which don't get the right combination of action and twisting "smart" plots and see a movie where the only thing I see is awesome battle scenes and the like.
So far I've only seen one movie with a perfect combination of action and scenario/story/plot, and that is V for Vendetta, which remains my favorite movie of all time.