That the film 300 came out either shortly before or during the writing of season three of Robot Chicken is immediately apparent, as the show milks the film for several sketches, including one of the highlights of the season.
This will only make sense if you've seen the film, of course. But if you have, it's about 100x more entertaining than the movie.
Now obviously that sort of craziness is not going to be to everyone's taste. And to be honest I do think that overall this season is the show's weakest so far. There are some very funny, very clever moments like the ones mentioned above, but I felt the quality was somewhat uneven as a whole, and had an unfortunate habit of drifting into slut-shaming at times.
Still, if wacky pop-culture-soaked shenanigans sound like your thing, the show definitely still has some shining examples of the form.