Dragon Age 2 is $5 today only on Gamefly. Worth it?
Definitely. I think it has some flaws certainly, but it had a lot of potential to be a great game. They were hurt by a very short production time.
The main problems with the game are recycled area maps and underdeveloped environments as well as a lack of interesting side quests and NPC factions. Most of the quests are very poorly executed fedex quests that shouldn't even be called quests because you simply find some random object in a dungeon and later in the game some random NPC suddenly gives you money and you have no idea why. They are so pointless it would have been better to have no quest at all.
On the positive side, most combat encounters on Nightmare setting are much more challenging and more tactical than DA:O, particularly if you constantly pause and micromanage your followers. The enemy A.I. is a bit more sophisticated, as enemies can steal your potions, go into stealth mode and backstab you, etc.
I liked the concept of focusing on the story of a normal person, a refugee with family issues, rather than someone destined to save the world from the Blight, and there were a lot of great moments in the story. Some of the companion characters were also very interesting, with excellent voice acting perfomances, particularly Eve Myles from Torchwood who played Merril, Brian Bloom (Varric), Jo Wyatt (Hawke), Gideon Emery (Fenris) and Victoria Kruger (Isabella).
However, the ending left a lot to be desired. I don't want to spoil it, but I'd say the choice of which faction to join and the faction questlines are not very well implemented.