WoW has become a rather poor endgame product when Activision took over the reigns last year. This was around the time they announced a controversial emblem change and released a rather poor Argent Tournament tiered raid. Nowadays, a new level 80 runs heroics over and over again and he will be ready for icecrown citadel. Geared 80's just run the frost daily/random bg/raid/facebook chat/ afk with (easy drake achievement here).

If you would've asked me this question last year when Ulduar was the epic tier, then I would say you should defintiely play it. Now, the game gets mind-numblingly boring after 2-3 weeks at being 80. If Wow keeps this emblem and raid structure for Cataclysm, then there is no hope for reviving that epic feeling in this game anymore.