I have 6 or so in a hedge row shaded by ornamental cherry trees. The conditions are not optimal as the cherry trees make it shady and very dry. I prune the Diana's down to 4-5 early every spring to ensure my privacy as the other side of the hedge row is a sidewalk.

The plants are not the most floriferous I have ever seen. I get a steady pour of flowers late summer and early fall. But never covered with flowers. I have very few seedlings and it isn't clear wether the seedlings are from Diana or migrating birds.

With fuller sun you might get more flowers. I'd say that given the suboptimal site and treatment I have given the Diana's, the performace has been good.

Diana is a great choice as it is sterile, so you don't have the million seedlings older varieties of Rose of Sharon produce. It blooms a long time for me. Cons are it doesn't leaf out until quite late and has no fall color.
I've heard that all the Hibiscus syriacus that have names from classical mythology--Aphrodite, Minerva--are also sterile, but have never had this verified.

Another con is that Japanese Beetles *LOVE* it. Something to consider if they are a problem in your neck of the woods.

I have an unnamed solid white ROS that I got as a seedling out of a friends yard many years ago. Its located on the eastern side of my neighbors large old pine trees, so it is shaded late in the day. I never water or fertilize just stand back and enjoy. I like to try and record first and last open flowers of as many of my plants as I can. Its very easy to forget to write down when they stop. Last year my ROS opened its first flower on June 8, and its last open flower was September 30! ROS may be considered too old fashioned and out of style, but there aren't many plants that flower for over 3 months! Here it is on June 23 last year....
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