It turns out to be quite confusing for new mappers that to save one needs get to right, click "save" button and get to left side of the screen, fill form there and use "upload".
Maybe it would be better to keep "save" and "upload" menu both on the right side of the screen?
It is especially confusing on larger monitors. As bonus it requires traveling large distance with mouse on each save.
What about just blurring and darkening the UI to draw the mappers attention to the right spot? iD already darkens, so all that would be needed would be the blurring.
Thinking about this, here's my ideal upload workflow:
The upload form is just another barrier to contributing.
To be clear, I'm not suggesting we wholly remove the save form. I'm saying that in my personal ideal world that doesn't exist we would never have to bother users about that stuff. That ideal informs my thinking about the UI, like how maybe it could be a popover under the save button instead of an entire inspector screen. But this is just hypothetical brainstorming!
Cool!
Quick mockup:

Clicking "Advanced" would essentially show the existing upload form. Clicking the warnings would open the Issues pane, or possibly enter some kind of "issue review" mode where iD takes you through each issue step-by-step.
This has the following advantages:
@quincylvania I like the idea and direction.
Before I forget: The post-commit-screen with the community index should still get a good amount of space afterwards. Maybe as a separate thank you layer.
About the mockup:
I think it would further benefit from removing the "basic/advanced" toggle to something, that shows the additional features on demand but has more meaning than "basic/advanced".
Quick idea:

For the last item: Is this really useful? I was wondering recently, if an integrated https://github.com/osmlab/changeset-map view might be more useful. Would that even be possible with an uncommited changeset?
I also don't love the toggle control. Maybe something like this?

On-the-map dif styling is definitely something I think we should do eventually.
I've been thinking even more about the save popover and I'd really like to try it. We should make saving as easy as possible for mappers—they've already done the real work after all.
Latest mockup:

I like this! The current design was really meant for the old sidebar, and feels rather cramped in the assistant panel, especially when using a phone. This new design seems very elegant.
I like this! The current design was really meant for the old sidebar, and feels rather cramped in the assistant panel, especially when using a phone. This new design seems very elegant.
I like this too..
Actually the current design really was originally in a modal dialog that appeared on top of the map, but we moved it to the sidebar years ago so that users could click on the list of items that they edited and look at them before saving.
Oh, cool! The old design definitely worked well with the sidebar, though.
background here: https://github.com/openstreetmap/iD/issues/2378#issuecomment-60131151
For the last item: Is this really useful?
As someone who does a lot of roving editing sessions (as opposed to targeted changes), I do use the change list as a way of jogging my memory, not necessarily to preview the individual features but at least to remember what kind of features I edited. Others may have different preferences depending on their changeset comment writing style.
Lately, I’ve found myself briefly opening the save panel for random-access navigation to various parts of the map that I’ve edited, without saving just yet. Maybe that should be a separate tool, which the user could also open before saving if they need their memory jogged. The right sidebar is getting rather crowded though…
On-the-map dif styling is definitely something I think we should do eventually.
A preview was discussed in #5974 and probably elsewhere before that. I think it would be a highly desirable feature, but also a complex enough feature to deserve its own issue independent of this redesign.
@1ec5 There's actually an open PR for dif styling: #6843
Most helpful comment
I've been thinking even more about the save popover and I'd really like to try it. We should make saving as easy as possible for mappers—they've already done the real work after all.
Latest mockup: