I am not in between drafts, but I've already started to see the critical weaknesses in the draft I'm writing. Perhaps the most challenging thing for a pantser is that so much of the first draft is spent getting to know your characters and your setting. Sometimes you know them right away. Sometimes it takes pages and pages to finally understand what makes them tick.
Granted, pantsers can do prep work just like plotters do. It's okay to sit down and write out what your main characters have, what they want, and what they fear. But sometimes the character you meet along the way is not the character you thought you were writing about. The second draft is so much better than the first because you're writing from a point where you finally understand the players involved and the setting. Really, it's almost like the first draft is the longest, most detailed outline one could write about your book and the second draft is really where you start.
I am anxious to get to the second draft of my wip. (Of course, I'm anxious to get to the second draft of a previous work as well, which is making for all kinds of internal conflict). :) Because of all that conflict (and because I recently finished reading Russell Brand's MY BOOKY WOOK), I've started a process I usually save for between drafts. I read a good book (in this case, Peter V. Brett's THE WARDED MAN), one I've read before, and I tear it apart. I read it as critically as one can. How often does he use dialogue tags? Why did he use that adjective? When does he describe people and when does he leave it to your imagination? And so on and so on. Question EVERYTHING!
The reason for this is because I pick up on what I think the author did right and then I compare it to what I'm doing. (I also don't use the same author for this process because then you can get fixated on a particular style rather than the commonalities of good writing.) Describing characters and places is my biggest weakness because I rarely care what they look like. It's the events that occur and the choices they make that matter to me. If they have curly or straight hair is inconsequential. Of course, not everyone agrees with me, so I have to make it a point to remind myself that that kind of thing should be included.
And in fact, as I read a good book so critically and see my own shortcomings, a sort of mantra emerges. "No. Do better." Those two sentences (or one sentence if I chose to use No as a clausal interjection) inform my entire self-editing process. I go over what I did and say, "No. Do better." Repeat and repeat and repeat until you can say, "Okay. That's better."