Pros:
Area loot
Companion crafting
Companion node looting
Sometimes the cutscenes are interesting
Heroics provide an alternative to standard questing
Star Wars
Cons:
World isn't very explorable
Mobs aren't very diverse in look or abilities
Quests objectives and mechanisms are extremely simple
My toons feel effective, but not heroic. I'll just inevitably win over and over and over.
Can be the worst (Class X) ever, making all the wrong choices, doing absolutely nothing noteworthy, and the story will still act like whatever you did was amazing - a hero of legendary proportions.