I priced out tickets using the new zone companion certificate for PHL-EYW. Paying passenger was $339 (on a $278 base fare), companion was $28 for taxes, total for both about $367. By comparison, a standard 'L' fare on delta.com for the same flights comes out to $491 EACH. The new companion fares in this case are over 60% cheaper than regular fares, and almost 30% cheaper than previous certificates (when you'd have to buy the first ticket at regular price, and then the second one was free).

There are still probably a lot of markets when the companion voucher (either old or new one) doesn't save much/any money, but this is one case where it's a definitely improvement.

Jeff