I've heard of it, but have never seen it in the retail trade around these parts. My I suggest you buy it and let us know what you think. I would if I had more space available.

Didn't have a chance to grow it myself either, but saw it today in someone else garden.
It came from the mail order co(Song Sparrow?) in a spring as 6" plug.
After full season in a ground it's still small, about 1x1'.
Now when it lost almost all leaves it looks like a small ball of tangled wires. I hardly was able to count 4 pencil-thick branches, rest was very thin branchlets with relatively small (3-4" the most) and rather flat(ish)/round(ish) flowers at the tips. Definitely not a conical shape. Somehow resemble Kyushu flower if you cut the top half of it.
I wasn't really impressed so far, but maybe it's just too young to show itself properly.
Is anyone willing to share your experience?

Well, as we have said before, some of Dirr's comments with paniculata need to be taken with a grain of salt. However, in his book he says he is not impressed with dharuma.

It would be interesting to see if someone has grown it longer

4 years later....
4x4' shrub with a minimal spring pruning. Blooms a tad later than 'Quick Fire', but earlier than PG.
On a scale 1 to 10 (10 being the highest) I would rate it between 7 and 8, but it could be usefull when full-sized cultivar is not an option.