I got Shaka Zulu in 2013 and it has at least tripled in fans. Even though it is not high in bud count (maybe 10) or branching (2-way), the color is just beautiful. It blooms in my zone 6b garden from the last week of June to mid-July, about three weeks.
It gets almost full sun, so it loses a bit of its lustre throughout the day, but is still very purple. This picture was taken 6/26/15 at about 6pm and I think it still looks pretty darn good even if the picture itself isn't the best, lol! You can also see in this picture that it blooms just above the foliage. At one time I had Francis of Assisi, a child plant of Shaka Zulu's and it bloomed just barely at the top of the foliage. I would prefer blooms that are several inches above the foliage.
This picture was taken on 6/21/15, and has lots of scapes to make up for the low bud count. I do not recall ever seeing rust on Shaka Zulu, a big plus!