While we think the default interface for World of Warcraft ain't that bad, most players prefer to tweak it with several add-ons. Some players have a completely different layout and interface, one that they've got accustomed to over the years.
It's only natural, then, that they would fear not being able to use those add-ons in WoW: Classic, but as Omar Gonzalez, a senior software engineer at Blizzard, told us during our recent interview, most modern add-ons will be compatible with WoW: Classic, as they share the same application programming interface (API).
World of Warcraft: Classic is now out, and the full interview with Gonzalez will be shared later today, so stay tuned for that.