Old DA is still available to stroll through too. I liked going between the two to see the differences.
Much as I like the new DA, I wish they'd found a way to keep the fog effect in some degree or other. I really loved the spookiness of stumbling through that stuff, especially when you'd see silhouettes of figures walking in it, only to have them turn out to be ghosts.
I forgot that the Shadow Shard had 4 different Task Forces that I unfortunately never tried. I heard that they took a long, long time to complete, which may be why no one I knew in-game ever wanted to do them whenever I asked.
I only ever did one, possibly two, myself (though I'm pretty sure it was one). I heard, but obviously cannot verify myself, that the later additions to the game- notably some of the Paragon Market items and travel devices like jetpacks, etc.- made it less of a slog and quicker to finish them.