'Carmen' is a wonderful, productive corno di toro type pepper. When they turn red, the flavor is delicious! It's a consistent performer here.
For me, 'Carmen' seems to be a little more cold tolerant than some other cultivars. It won't survive a freeze, of course, but it continues to ripen fruit even when the temps get chilly (although more slowly).
Henderman & Critter are right about the stubby little pepper fruit. They seem to be the result of partial but poor pollination. The resulting fruit is usually seedless or contains a few feeble-looking seeds.
Critterologist is actually the one who got me addicted to 'Carmen' peppers over a decade ago. She had written an article about non-bell sweet peppers on Daves Garden. She also had a seed offer at the time and that was the source of my first seeds of 'Carmen' (and 'Gypsy').
One day, I really want to try the golden version called 'Escamillo'.