Had to Google Ninebark! I'm familiar with Spiraea but now have a pre-novice grasp on Ninebark. Interesting shrub!
Ninebark is one of my favourite shrubs to add colour in the garden and the bark, as you've shown here, offers winter interest too. I have a Summer Wine Ninebark, similar to Diablo but not so dark, but love the newer introductions including Center Glow Ninebark. The only complaint I have is they seem to be prone to aphids. I usually just give them a heavy blast of water from the hose every couple days or so while the pests are visible. Some years are worse than others, as is the case with most plants. Definitely one shrub I recommend highly.
I have 'Diablo' in my garden and it is one of my favorites