To anyone struggling away trying to get published, I do sympathise. It must be about 30 years since I submitted my first completed novel to a publisher. (There had been several attempts at novels prior to that which never got finished!)
They liked the portion and outline and asked to see the rest, which they then turned down. I can now see why. A while ago I found that MS in the bottom of the wardrobe during a de-cluttering binge and after a quick glance, I dumped it in the paper recycling -- and that was my only copy. It had been written in the Dark Ages, pre computer. But I can now see what was wrong with it: the prose was flat and the story structure was all over the place. I've grown and improved a huge amount. A few interesting ideas have been salvaged and put for recycling, but none of the existing prose was usable.
Since then I've completed and shopped around two more novels. The reason there weren't more is that raising two kids, earning a living and gaining a degree as mature part-time student take up a hell of a lot of time. But I did write short stories during that period and managed to sell 3 of them. I also wrote a large chunk of another novel, the opening of which I posted as part of International Embarrass Yourself As An Artist Day. I actually think that one is salvageable, though as it stands, it leaves a lot to be desired. It was written at the point where I'd grasped Show Not Tell, but hadn't worked out how to avoid showing everything *g*
I then completed novel #2, but after a very near miss I eventually gave up on it after two agents failed to sell it. Yes, the bad news is that even getting an agent is no guarantee of publication! (That's the novel that's webbed at my other LJ helenkenyon)
Novel #3 is currently at a US publisher, assuming it didn't get lost in the mail.
Meanwhile I'm ploughing through novel #4, which is also novel #0 ie one of the unfinished ones from my teens and there are novels #5 and #6 forming an orderly queue to be written next.
I do still have hopes of being published one day. Being a writer is not a job that involves heavy lifting, so age is not necessarily an impediment. *g* But seriously, I can see that I'm getting better with each novel I write. I have more control and though my good bits are not necessarily any better than the good bits I wrote 20 years ago, the prose is much more consistent, there are no cringe-making bits and the story structures work so much better.
Right now I'm trying to achieve a balance, that elusive Middle Way of Buddhism. If I treat writing as a hobby, I pick it up only when I feel like it and drop it when it gets hard or I'm a little pushed for time. That way I don't make any progress. If I treat it as a professional job, I become obsessed with publication as a goal and also I spend too much time writing to the detriment of other things, like relationship and home comforts. Because there is no guarantee that I'll ever sell a novel, however good a writer I become, that's not a good route to go down either.
Some useful things have been achieved this year. I finished the polishing draft of Moving a Mountain and started submitting it. I also joinednovel_in_90. Through that I've found my ideal writing pace, one that I can sustain over a long period and yet will still produce a finished and polished novel a year whilst still working full-time. The novels I've written in the past have taken 3-7 years, which is just no good for any kind of professional career.
Otherwise it's just business as usual. Onwards and upwards!
"Try again, fail better." 
 This was where I learned the hard way not to send out a partial and outline of a novel that is not actually finished and polished and ready to shoot straight back to the editor who shows an interest. If I'd been able to do that, I may well have sold A Legacy of War in the late 80s. As it was, by the time I had the rest of the story finished and fit to send, the company had been taken over, the editor had moved to another publisher, the original publisher had moved to new premises and when I finally queried, no one had ever heard of my MS.
 Gail Sher in One Continuous Mistake, paraphrasing Samuel Beckett.