You can run through it at least. Not the path with the cells and the switch though.
I wasted a lot of time slogging through the long way since I didn't think I could make it past the gates in time. New Smelter was tough (especially for solo NG3+) but the route there was much more annoying.
Then I realized you could take the high road through the gates, take a flying leap off the top right ledge, past those giant iron warrior enemies, and right to the fog door. I only bothered to kill the sorceress by the 2nd gate lever and the possessed armor at the end of the ledge where you need to jump.
Edit:
Is the DLC worth it, is it as good/long as Artorias of the Abyss? I'm thinking of getting the season pass but 24,99 is pretty steep unless it's at least as big as the expansion for DS 1.
Each piece of DLC is smaller than AotA but all three together will be considerably larger. If you liked DaS2, you should definitely pick up the DLC. Honestly I think these two areas are better than anything from the main game. Especially the DLC that just came out, which is some of the best stuff of the entire series (and I don't say that lightly).
I don't know when they started working on the DLC but it seems clear that they paid a lot of attention to DaS2 criticisms and went out of their way to make more interesting and complex levels. DeS and DaS1 will always be top dogs for me, but this team has really elevated their output.