It’s a carbon fiber composite, lighter and strong then steel, perfectly safe.
The seats sure look comfy.
Airbus and others have been using composites in their aircraft for years. As long as inspections are kept up, the use is perfectly safe.
Safe, but doesn't have the 'give' that aluminum does in a minor accident. Composite planes tend to shatter and absorb less energy in a crash. There is a long-running debate among home-builders on this issue. Big planes crash so infrequently that it's not going to be an issue.