Publish Or Perish?

I worked on my first novel for a long, long time.  I got the germ of the idea in the summer of 2001, which is a scary amount of time ago, and a core part of the story was radically altered by a seismic shift in history that autumn.  The first draft didn't take me particularly long to get down on paper (or on a VDU - yes a big boxy CRT monitor was still in use in those dark times).  It took maybe three months or so for that seed to sprout into a full plot, and then I set about tweaking it.  And tweaking it.  And tweaking it.  As a wise man once said, no novel is ever finished, merely abandoned, but when you're not yet a fully established author with no publishing house breathing down your neck with their deadlines, there can be a tendency and temptation to just keep fiddling with your story, rather than try to get it in front of other people.

And here we are in the year 2012, with Underworld finally available on Smashwords.  My question is, did I do myself a disservice waiting so long between writing it and actually saying "ok, fine, here you are world, this is what I have done"?  The novel could always use extra polish, what book couldn't?  And the second book I have written and am shopping around at the moment is definitively better, but that's what happens when you write a book.  You learn so much, then you realise after the second book you still have so much to learn.

So what do you think?  Should you publish (or try to) fairly early, or let a story mature and carefully craft it over a period of months or even years?