Gunbuster manages to do in 6 episodes what many anime fail to do in 20+, tell a story that is both coherent and rich. In a nutshell, the show is about hot chicks in space with mecha and Norio Wakamoto. You already have a show worth sitting through at least 12 episodes right there. However, Gunbuster manages to go much further than that by establishing a thrillingly Lovecraftian enemy in a setting that explores the realistic implications of travelling at or near light speed. The show doesn't shove the science down your throat (unless you pay close attention to the lecture segments), but rather weaves the scientific concepts into plot elements that are emotionally jarring at their best.
At first glance, the story reminded me a lot of Ender's Game: the idea of recruiting young soldiers to go into space and train to fight a mysterious, unifying threat to mankind. The story ends a lot like Gurren Lagann, however. Using the power of perseverance to overcome the seemingly impossible.
The show reeks of 80's sensibility, so it can appear a bit dated at times, but I don't think this distracts from the enjoyment, although it can make the theatrics a bit cheesy at times.
The only real flaws I could see with the production probably had to do with shoddy subbing and aging sound/graphics. Once you get past that, you can begin to see the classic masterpiece that Gunbuster really is.
