People say it's gonna be way harder than WotLK.
I've been playing since TBC and I've experienced prog raiding, (t5 & t7/8/9) with a high-end guild, and honestly I consider myself pretty good at this game. When I'll level I plan on running dungeons with guildies, etc.
Will I consider cata "hard"? I don't think so. The difficulty meter is different for everyone guys, someone new might have more trouble.
Blizz said it would be harder. Every said it. For me, I don't think it will be a dungeon wipe fest, or I'll have trouble making quests and downing raid bosses, I think it'll be just like WotLK; different for everyone. No, I'm not bragging or anything here, just what I think.
Just my 2c.