I've said in the past that enhancement is in a good place in 4.3, and that's the truth. Despite some really awful itemization and some as-yet-unresolved issues with the spec, enhancement is remaining a strong middle-of-the-pack contender. In non-cutting-edge raid groups that don't have multiple Dragonwrath-wielding casters, we're even better.
Dragon Soul is a great instance for enhancement in 4.3 because it offers a variety of fights. Some play to enhancement's strengths, some highlight its weaknesses, and some fights are Ultraxion and your DPS spec doesn't matter, provided you can push buttons and click a shiny purple dot on his screen every 45 seconds. For the purpose of brevity, I'm going to assume you're familiar with the normal-mode mechanics of these fights (and if you're not, some are conveniently covered by my frenemy Tyler Caraway in the Ready Check column) and just speak to how enhancement specifically fares on these fights.
There's nothing particularly special about Morchok for enhancement, except if you're doing the fight on heroic. Shamanistic Rage and Glyph of Stoneclaw Totem make Morchok's Stomp damage negligible, but Stomps don't really hit hard enough on normal to worry about. However, if you have a healer in line of sight during a black phase (and you've done nothing in recent memory that would cause them to hate you), Glyph of Stoneclaw Totem and Shamanistic Rage will let you stay on the boss for most if not all of the phase. If you don't have a friendly healer, enhancement still fares better than most melee on this fight, as cast Lava Bursts and Lightning Bolts still hit hard.