FLCL is one of those series that just 'wow' you.
The level of detail and quality of the animation was astounding at the time, and still shuns most newer anime series today. Considering this was released 10 years ago, it simply hasn't aged in terms of animation, or story. FLCL is categorized by most people as a 'you either get it, or you don't' kind of series. If you don't dig crazy action scenes, over the top scenarios, and prefer you anime to be more serious/realistic, this series isn't for you. But if you're like me and love anything unique, 'out there' and fast paced, you will adore FLCL.
Set in the town of Mabase, FLCL follows the 12 year old protagonist Naota Nandaba as he copes with crazy adults, a truanting love interest, a robot that spawned from his head and oh, a 19 year old alien who wields a guitar like a sword and drives a flying Vespa. Ths series is mostly fixated on Haruko (the guitarist alien) and Naota as they cope living together and trying to overcome the town's evil corporation Medical Mechanica. Yes it sounds bizarre, and that's because it is. Some episodes won't make sense the first time you watch it, meaning you'll have to watch most episodes more than once to understand it properly. But it's worth it.
It just doesn't get boring. The over the top action, the strange characters, the outlandish dialogue. It's all fresh and entertaining. And the amount of stuff that happens in each episode is enough to satisfy anyone. One minute the cast are in a baseball game, the next a bomb is hurtling towards the city from space. It's crazy. It also has an amazing soundtrack by The Pillows, a Japanese band with a roster of great tunes. Everything comes together to form an amazing package that was just way ahead of its time. The voice acting is good too.
In short, watch this series. Yes it has a story that makes no sense, and only has 6 episodes, but just watch it. It may be the most entertaining and funniest anime series you'll have watched in a while.