Nobody has ever said that FusionIO cards were slow (because they aren’t). Especially if you compare their performance to regular spinning media, or high performance SANs. After all, no SAN will allow you to measure storage write latency in microseconds.
Anyone that has had their database reside on a FusionIO card has had nothing but good things to say about them. The only thing is that a lot of people are probably not making the most out of the cards that they have. FusionIO cards actually have an artificial performance restriction put on them, and can go even faster than they do now.