I have two ninebark bushes. This is the flower cluster on the Dart's Gold which blooms well even in part-shade . The shrub has also grown really fast so that in its third year it is 6' tall. Of course being a bit short of light, it is ganglier than it would be out in full sun. I like the yellowy green leaves that brighten up the shady spot and I'm quite happy to have it overgrown as I planted it to crowd out the wild maple raspberry plants that can be so hard to control.
It's hard to see where it begins and ends because there is so much green around it, but it it probably close to 8' at its widest part. It could be pruned if someone wanted a tidier plant and in full sun it would be shorter. Hardy to zone 3, maybe even 2 in a sheltered spot.
The other ninebark is Coppertina which is a cross between a purple ninebark and the gold ninebark. The leaves start out yellowy-green and then gradually turn sort of bronzish. In the fall, some of the leaves will have pinky red markings. My Coppertina is much tidier than the Dart's Gold even though it is in a pretty shady spot, and it has only grown to about 3' tall. The colour is ever changing over the season which makes it an interesting plant. Both ninebarks are bug and disease free and don't seem to mind dry or wet weather. Very easy shrub to grow.