Ultimate Cosmic Power ... sort of
Overall: comfortable, flexible, and has a fit that won't leave you feeling like you're wearing a suit of chain mail.
Synthetic mesh breathes pretty easily (although all these 'pressure-suit' style armor tops are somewhat hot IMO), and the venting in the plates seems to do the trick. Shoulder and chest plates saved me from damage after I botched a landing at the Canyons and ended up rolling into a rock-lined ditch. Sold on this tee after that.
Waist closure fits great and has burly velcro that doesn't budge. Once you get this fitted and toss a jersey over it, it's not going anywhere. Spine protection isn't rigid, but like I said above, it saved my butt already. I couple this with some POC softie-style elbow pads as well. Fully rigid arms feel too restrictive.
Racers or regular tech-aggressive riders might look at something with longer arm protection and a rigid spine protection ... everyone else would do just fine with this tee.