In all threads about new expansion I see lots of pll bashing Cata. Many pll say it was worst expansion ever. I did play since May 2005 and I strongly believe it's second BEST expansion after BC. Why? Everything about Cata was PERFECT. I'll explain now why.
1. Leveling, core of the start = amazing fun because you COULD fly. Wanna not start level in one zone? Choose another. Leveing in Hijal is amazing, I still have a lot of fun lvling there on my alts. Uldum, nice storyline and fun quests. And that quest when you kill 1000 gnomes... PRICELESS . Not only that. They revamped old zones so nicely that it became fun to lvl new toons :P. And they added so many "EPIC FUN" quests. Like Sylvana's one. Or the one in badlands. Without Cata we would still grind old boring quests.
Now to people who say, flying mounts=no pvp. I had tons, TONS of fun world pvp in Vashj'ir and TB. In fact I killed so many people in world pvp during Cata I didn't kill since vanilla.
2. Dailies. Never, never felt like something you HAD to do. And esp those in Hijal were amazingly fun, there were even dailies which were easier to do as healer.
3. Lore. Involving Thrall, one of the main lore characters. Even though I didn't enjoy much doing "Thrall specific quest" on many alts, doing it first time was very inspiring.
4. Raiding. Actually Cata was first time when I started raiding very seriously. Because content was worth it. Remember emotions when you had to jump to lava on Nefarian hc.
5. EPICNESS. Yes. It came to unreal level in Cata. Do I need to explain why?
6. Dungeons. DUNGEONS WERE FUN. You needed some afford to complete stuff and when you finally completed them, you felt so good.
My point is, I see no reason why people hate that expansion.