It depends. Mostly I just carry on. The bad stuff can mostly be fixed or thrown out. The most valuable thing is the period between finishing it and when you reread it pretending you've never read it before and definitely didn't write it, the few weeks when you allow yourself to forget it. Then when you read it as a new reader, sometimes it's obvious what to do to fix anything that needs fixing. I'll also send stuff out to people whose opinions I trust, explaining that until it's done they aren't really allowed to say much more than "Is there any more?" but once it's complete I'm happy to take all and any input onboard. Just as long as no-one minds me throwing it back overboard as soon as I start rewriting.

When I was working on my novel for NaNoWriMo a couple of years ago, I posted it her as I wrote, but tried to make it clear that while anyone was certainly welcome to send comments of any kind, I was also perfectly free to ignore them if they were critical. It got so I would recognize the email addresses of people who wanted to argue with me about things, or who were undoubtedly going to point out what they thought were mistakes (or which, in fact, might have actually been mistakes--it was a first draft, after all), and I just didn't open those emails.

I read an interview with a writer a long time ago who said that while you're writing a book, your friends and family should not be allowed to give you any criticism at all, but should simply be encouraging, and I totally agree with that. While writing, a writer is certainly aware that there will be inconsistencies, redundancies, etc., and those can and will be fixed later. The most important thing is just to finish, get to the end.

Speaking of which, it's probably been long enough since I finished Fallen Angel that I've forgotten most of it and can look at it with new eyes. Maybe this winter I'll get back to it. I haven't given any thought to NaNoWriMo this year, but hm. Maybe.