My response is hot and cold.
Getting availability is my only bone of contention right now. They don't seem to make this very easy at all, I always feel like I'm throwing darts.
However, once they find the flights, things are going exceedingly well these days. I arranged for a ticket for my sister to Buenos Aires with about 40 days notice over the busy Christmas travel season. I'm beginning to think it was pure luck. They issued the tickets promptly and we are ready to go. A good use of miles.