Diamond is very impressive. Not just the hardness or the high refractive index, but it has the rare property of being an excellent thermal conductor whilst being an excellent electrical insulator at the same time. However, like it's period 3 counterpart, silicon, it can also be doped with atoms containing fewer or more electrons and this can be made into semiconductors. Unlike silicon, however, doped diamond on pure diamond substrate will tolerate much higher temperatures whilst typically having lower electrical leakage and better switching characteristics. As the lattice is more compact than silicon, smaller process sizes are probably possible with the same sort of atom-count-per-gate too.
Forget the processor technology you know. Diamond-based semiconductors have the potential to raise the bar for clock rates so much higher that we're going to have to find completely new ways to connect components together as the gap between what's possible on-chip compared to what is possible between chips is could to open up a long way. Heck, boron doped diamond is even super-conductive under the right conditions.
So I'd say they are very impressive. They're just not especially impressive to look at.
As if diamond is the only allotrope of carbon...
