I omly played it for a year or maybe two tops just before and through Cata. Hated the grind so mostly played a Death Knight tank and joined a random group looking for a tank in all chat that was a blast to play with. Lots of late nights, and had fun, but didn't miss it when I quit after not wanting to spend money on another expansion on top of the monthly sub.

If anything it soured the concept of grinding. If a game isn't fun from the outset I don't even bother with it. Leveling/upgrades are fine as long as it doesn't feel like I need to for the game to be fun.