I've been trying D&D: Heroes of Neverwinter after receiving several invites from various Facebook friends. I played a cleric up to level 3, but I'm not sure I want to continue playing. I simply find it too annoying that three quarters of my group consist of characters that aren't my own. I already disliked Dragon Age Legends for exactly the same reason.
I can see how the developers got the idea: Playing a Facebook game with your friends doesn't sound all bad. But in the end the problem becomes exactly the same as with playing World of Warcraft or other MMORPGs: You can only play with friends of an appropriate level. If you friends are much stronger than you, your own contribution is minimal and thus boring. But if you outlevel your friends, their lack of progress is holding you back.
Heroes of Neverwinter is somewhat better in that respect than Dragon Age Legends, because you can always hire mercenaries instead of friends in the tavern. And I see that as a trend in MMORPGs as well: Games like Guild Wars, SWTOR, or Diablo III all offer NPC mercenaries / companions / henchmen to help you over your lack of friends.