Hello i was just wondering about the difficulty of the cataclysm bosses as for i have quit and do not know how they match up to the last expansion pack are they the same harder and whats the hardest boss on wow right now ? thank you
They are certainly harder than WOTLK that's for sure. How hard varies significantly boss by boss. All in all I'd say the first raiding tier of cata is as hard or harder than the final Raiding tier of WOTLK. The normal modes are about the same, but the hard modes are harder (with the expection of heroic lich king).
As for the hardest boss:
On normal, most people seem to agree that it is alakir on 25 man, and Nefarian on 10 man.
On Hard mode, most people seem to agree that it is Alakair or sinestra on 25 man, and Neferian. or Chogall on 10 man.
10 man and 25 man are about even in difficulty now, but some fights lend themselves to 25 man more than 10 man, and vice versa. For instance Nef is harder on 10 man due to the need to either use three tanks, or two tanks and a kiter, and the way healing works on that fight. Alakair is harder on 25 man due to the fact that space is a premium on that fight, and 25 people take up more space than 10 people.