I'm in that middle place with my craft – aware I've got strengths, and pretty sure I know what those are, but blind to my weakness. The middle place is... difficult.
At the start of your writing career, you can feel the problems in the prose. As a new writer, I could feel the story wanting to get out but that it didn't look right on the page. Honing my craft improved the flow of my words, but there's a gap now between what I think I know, and what I don't know. Rather like a Johari window, I don't know what I don't know, and I certainly cannot assess the problems in my own prose because, well... how do I know what's good and what's bad if it's as good as I can make it? What skills do I need next? What's lacking and what's on point?
The editor's work was INVALUABLE (in all caps. Yes. That good) in verifying exactly where my weak spots are. Here are some of the things I learned as a result. Number 3 wasn't something I expected, and surprised me a lot.
It confirms and points out weaknesses
It was a professional assessment that showed me exactly what I need to be working on. It means I can now compensate for my natural habit to let the dialogue play out, and be conscious of the need to add action beats (I just need to careful not to go too overboard now, of course.)
Writing improvement: shaking beats over the prose like sprinkles has improved the flow by quite a lot, disproportionate to the amount of words used.
2. Shows the writer specific things to improve and where in the text
It helped me target exactly where in the scene I needed to add something. That vague sense a reader gets of 'this isn't quite right' was spelled out for me. Or, really, commented on, which is better.
Writing improvement: zoning in like that helps me spend time on the things that need it, not what doesn't.
3. Confirm the writer's strengths
Just as it confirmed to me my weaknesses, the editor's notes also confirmed my strengths. When we don't know what we don't know, we can be blind to our strengths as well as our weak spots. Confirming that characterisation, fast-pace plot, page-turning action and dialogue that leaps off the page is indeed a strength of mine and not a fancy in my head, was very very powerful for me and, yes, for my confidence in my work. I now feel a lot better about these elements, knowing I have them down pat.
Writing improvement: more let's say confidence and knowing I don't need to do any further work on those elements.
4. Helps develop a writer's professional language
You know when a reader comes back with 'I liked this bit, but something was off'? A beta reader is a reader in your target audience, not necessarily a writer themselves (that's more like a critique partner). Having an editor pull out specific elements and point out what the names for them are, meant that I could start to look them up and dig into them deeper.
Writing improvement: helps me hone and develop my craft.
5. The all-important industry assessment
I know I love my books. My readers love my books. But where does it fit, and what does the market look like? Having an editor weigh in on exactly what the target market is and why it fits is so, so helpful in marketing.
Writing improvement: helped confirm and fine-tune the category and genre.
All in all, a very good experience.