Well the entire world has changed since the Cataclasym so you the 1-60 content is new. The Burning Crusade is 60-70 and WOTLK 70-80 and Cata is 80-85 so you dont need any of the expansions untill you hit the cap. Also Id be glad to play with you on alliance or horde. We could even do Recruit-A-Friend if thats still around if I remember right when in a party with a recruit a friend you get triple the Exp
Not only do you get triple experience, IIRC you can grant levels up to level 60 and you each get a rocket mount.
As for the haters, WoW is one of the few games that brings them out of the woodwork (Oblivion seems to be another on here). Most of them have never played the game or only touched the surface. WoW has a vast amount of content, a deep story line, excellent gameplay, and tons of people to help you if you ever get stuck on something. If you ever need to get hold of a GM for some in-game problem you usually get a quick response. (unlike other MMO's where they're non-existent)
Just ignore them. There is a reason why Cataclysm had the best first day sales amount for a PC game.