Do not be deceived by the quiet, mellow first scene. Buckle your seat belts. And preferably wear a G-suit as well. You about to experience the biggest roller-coaster ride in all anime.
What is FLCL? Unfortunately, this high-budget 6-episode OVA by Gainax is indescribable. Anything resembling a normal plot about 12-year-old Naota having an intimate moment with his elder brother's girlfriend Mamimi is completely smashed to bits in less than four minutes from the opening. The arrival of Vespa-riding Haruko and the quite-delibrate pedestrian accident that follows mark the path down the road of insanity and sheer thrills. There on is non-stop edge-of-seat momentum that does not wait for you to catch your breath. So tremendous the action, FLCL is just about the only anime title that almost makes one feel the physical motion and impacts beyond its cool art quality. That which remains unprecedented to this day.
This heightened level of visceral experience is achieved not purely with genius screenplay devising, but by mating the scenes with The Pillows' rock discography. FLCL is without a doubt the Exhibit A of conclusive evidence that great visual presentations combined with the right type of music can erupt into fanstatically epic levels. It becomes really easy to figure out why The Pillows is one heck of a revered band in Japan.
Having said all that, FLCL is not going to sit well with many. Much like Neon Genesis Evangelion, Anno Hideaki's influence is too strong to ignore. This show is chock full of abstract concepts, hidden messages, symbology that can be taken many ways. If you want a plain-dead storyline where you don't have to think about what the characters just said, you will hate this show. In fact, the entire series was fabricated and directed in a rather seat-of-pants manner, but still the end result is a string of engaging events - even when they don't make sense on first look. There is not one single boring scene at all. Well given that it is only six episodes, there is absolutely no time to include boring scenes.
Love or hate the "story", but there is no denying the cast of characters with their excellent seiyuus have achieved a deep impression in the anime industry. A pity though, that some interesting characters with the potential to contribute weren't given time to develop. Regardless, it is hard not to be attached to the main characters as they seek to find meaning in their lives and laugh at their silly and sometimes inexplicable actions. Literature students have had - and will continue to have - plenty of opporunty to analyse this production from all angles. This is one helluva ride, start to finish. Finally, Gainax gets to finish a series without messing it up. 
Overall rating 10/10
Explosive action; literally visceral; lasting characters; The Pillows; pure style; raw entertainment
No real point; mind boggling; some underdeveloped characters