I have finally tried Tungsten. Here is what I think.
The +I find the overall design gorgeous. Great work, very modern and aesthetic. Congratulations. Believe it or not, a gorgeous UI gives me more musical inspiration. For example, both Sonitus equalizer and LP EQ are efficient plugins, but I feel "more powerful" when using the superb LP EQ. Design is very important to me.
The -But after one hour of work I decided not to use Tungsten anymore. I switched back to Mercury. I think that this beautiful theme is not comfortable for some people who are not at ease in dark environments. Especially people who wear glasses because they are myopic: they often have a poor night vision, therefore a dark theme is not recommended.
ConclusionThe themes are a wonderful addition to SONAR, thank you. I hope that we will soon get a new theme, for example "Aluminium": the same gorgeous, modern design as Tungsten, but with more clarity... and the colour strips!