It depends heavily on your level, server, and time of day/week. This past weekend, I was running Athiss and Hammer Station almost nonstop as a healer. Now that the weekend has passed and I want to do higher level stuff, I've given up on flashpoints. Having to go back to grinding quests has drained a lot of the fun out of the game for me. I'm sure other people enjoy questing a lot more than I do, but to me it's kind of dull, comparatively.