Surprisingly easy to pick up if you know Arc. I can't switch to it entirely but I've made red relief maps in it and I'm really impressed by some features.
After being forced to Pro I would be staring at this with nostalgia and sadness. A decade of work to optimize what I need out of it and I had to start all over with a laggy, crashy POS that constantly forgets my damned pinned tools.
RIP homie.
Pro did make my output maps better though, I will say that.
I was supposed to organize the upgrade to pro at my workplace - then I got an offer I couldn't refuse somewhere else. I feel bad because the guy who replaced me is struggling to get to grips with arcmap, and somehow will need to oversee the transition...
I'm using pro at the new place, and while I don't like a lot of the changes, map series are indeed fantastic. No more changing layouts a dozen times to export new versions of a project!