I expect it to be a feature I won't participate in except with/against my guild. If people on your faction/server challenge you and you win, they'll bug you for more games until they win. And if they win, they'll never let you hear the end of it.
I told this to husband and he said "The reasons you dread it are the reasons it will be popular. Lots of people want to be able to do that."
I figure he's right, and I hope people enjoy it, but I expect to answer non-guild challenges with "/forfeit, grats on the win."
I do plan on playing against guildies and getting tips from them to improve Plum's performance, though. Looking forward to it.