The new weapons and bosses are nice, but what I'm most interested in is the Tax Collector NPC, mainly because no one really knows much about what he'll do.
My guess is that he's there to discourage players from making extremely simple houses for NPCs. Like, for each npc, there will be a monthly tax based on their rooms. There would be some simple modlifiers (Is it lit up by a single torch, or is it lit up by lanterns or chandeliers), as well as NPC specific modifiers (The Angler wouldn't be able to pay much, the Cyborg wouldn't care what comfort item his room was stocked with, the Dyrad would give more if you had corruption/crimson enemy banners in her room, but less with purity/hallow banners)