They made a lot of changes this season to weapon crafting and modifying that’s made it much easier than previous seasons. There’s also a couple things that they made available across all difficulty tiers instead of the two higher ones. I haven’t looked into specific specs, but I believe they’ve also buffed a bunch of the skills.
I don’t know about mtx, but the paid battle pass is really only cosmetic stuff and doesn’t affect core gameplay, if that’s what you’re worried about. There are things called “smoldering ashes” which serve as season permanent buffs, but they are available on the free battle pass, so everyone gets those.