I did indeed try out OpenProducer. From my little test drive, I'd say the functionalities work very well and do exactly what I'd like them to do as a musician. I'm definitely thinking about setting up a couple of these babies for my projects.
I think the user interface works nicely. I know Drupal, so that helps me. I have to say that I'm more and more convinced that trying to simplify things too much is a bit of a fool's errand. Simple is what Wordpress does, it does it well, people know it for that and they like it for that. Drupal is more complicated, but it's more powerful. You have to play to your strengths. So to me, the menu works great. I'm sure the roles still need some tweaking, but in general my impression is that the UI is very good.
The only weakness I saw was in the looks. The theme obviously needs some love. A bigger challenge, perhaps, was in the color customization. As it is, the "color scheme" interface lets you customize about 15 colour settings, and it has that nice round/square color selector. The problem is that you have to manually adjust each of the 15 settings (I didn't like the presets), which means you have to know in advance what value you want, which means you either have a professionally designed theme (which I don't think most of yours users will have), or spent some time trying to cook up something with online tools like http://colorschemedesigner.com/csd-3.5/. It would be nice if something like that existed in the interface itself. I thought the 'Color' module did that and I activated it, but speaking as the whiny and ungrateful user, the process is still fastidious and the results less than impressive.
The only modules I know to that effect are already installed so I can't make any technical suggestions. However, I will say that improving the color scheme selector is, based on my admittedly limited trial run, the only thing missing before you have a very exciting distribution indeed.
Ah, and it would be very nice if the text in front on the image gallery had a semi-transparent background, which would make the text easier to read. I could open an issue for that if you like.