They worked, sort of, though it was just as easy to type what I wanted to say and hand the phone to people to read themselves. It wasn't very fun or liberating, either, because typing on that itty bitty on-screen keyboard takes too long. I gave up on the cool technology pretty quickly in favor of nodding and grunting, and by the time that started being really annoying, I could speak again.
I hadn't thought about this until just now when I found Low Cost AAC Apps for Speech, via Livingwithdisability. I hope I don't need to have surgery again any time soon, but if I do, some of these apps look like they'd serve the purpose better.