My subscription has been unbroken from day one, but I totally couldn't get into the Vanilla -- all it did was constantly remind me how much better the game had become after so many polishes and tweaks lol. I just kept thinking, "Oh, right, that's why they changed that, it's much better now."
Having said that, most of the folks I know who still play WoW think I'm crazy and that Vanilla is fantastic, so... I hope you like it! ?