Well, this is an anime by Gainax, so if you were expecting anything such as amusing and self-aware fan service, interesting characters, oodles and oodles of symbolism, and an unconvetional yet fitting ending, then you get what you wanted. FLCL isn't for everyone (as anything in any medium of entertainment is), but it is enjoyable but those who can appreciate it.
Personally I really enjoyed the less-than-three hours that I devoted to watching it once I got all of the DVDs (along with the box set, through hard searching online) together and watched it all in one sitting. Fun anime, nice humor, homages and references that I liked to catch (and miss), surprisingly nice depth to its characters (particuarly Ninamori; shame she only got one episode devoted to her), great animation and artwork (Sadamoto never fails to impress with his character designs), and finally a memorable soundtrack.
One thing that I did find intriguing was that the OVA applied a few experiments in animation, which was, in my opinion, a successful attempt.