Gurren Lagann starts off as a really interesting anime. Humanity has been driven underground following a war with an overwhelmingly powerful species. We start with our two heroes Simon and Kamina, the latter being a trouble making teenager and the former being the young boy who worships him. They find a mysterious robot while digging rocks, and use it to escape their underground prison with the help of Yoko, a girl who arrives from the surface. From there they engage in a thrilling adventure filled with fun characters, dynamic fights, and a certain vigor that can only come from the honest enthusiasm of the creators themselves. There is heartbreak a few episodes in, and I must admit I did not see it coming. It really serves to compel the audience to see it through to the end.
However, once the show reaches the halfway point everything goes immediately downhill. They end the first arc by defeating the main villain, and it seems like the show is over... until they do a time jump to about ten years later. From here the story enters a long, rapid downhill spiral, ruining certain characters, introducing ridiculous plot elements, and frankly feeling awfully exploitative for what started off as such a fun series. The last half may just make you angry that you didn't stop half way. It certainly did for me...
If you watch just the first half of this anime, it's actually quite good. Just make sure you stop after the first arc, or all that goodwill will quickly evaporate.
