All DA2 DLC Review

You forgot the Dog – as I remember the Dog is the part of the Black Emporium DLC.

The Exiled Prince is a good DLC, worth playing, because of the Chantry relation, especially Elthina, Leliana's investigation... the Grand Cathedral, the Divine's (possible) intentions... and I found Sebastian is an underrated character.
Sebastian is a perfect example of a "good weather" pious person.
He fights with his demons (he's not possessed, but has a demon army in his head to fight), and until the vengeance inside him doesn't tempt him, he's a good person, but easily falls.
At the end, he's the real opposite of Anders – according to my explanation.

The Legacy is the "must-have" DLC – especially because of the Inquisition, and also because of Hawke's background.

Mark of the Assassin... a controversial DLC to me. I should say: I do LOVE it. Fun – like a family vacation. Yes, the puzzles, are very good. The characters seem happier here – like they released out of Kirkwall – especially Anders, but everyone else as well. But... there are some good question about the DLCs lore... And true, that –as Varric says– not a big sin stealing from an Orlesian noble, and I can imagine, Hawke accepts such a shady adventure – just for "the good old times" – as a fancy noble guy too (noble social calls probably too boring)... but why would Hawke have reason to support the Qunari... – true, in Act2 not that unimaginable, before the Arishok became enemy. (I played it in Act3 – and while I don't hate Tallis, I found really hard to support her.)