Hey! Yeah, there's a huge summary I made for the Warlords Of New York OT. My short answer for what's changed since launch:
- Targeted loot - makes it MUCH easier to farm builds. Basically, you can filter the map and certain areas/missions drop specific weapon types/brands/gear sets more often. This is a layer of loot that's on top of what you'd normally get. So if you need a Providence chest and backpack, just go to a Providence area, farm it, and you'll likely be swimming in options soon enough.
- Streamlining of gear system (Skill Tier replaces skill power, no red/blue/yellow requirements to unlock talents, talents are only on two pieces of gear (Chest/Backpack) but are more powerful than they used to be, can see on piece of gear how close it is to a god roll)
- Oh yeah, because the old gear system worked on a budget system (one high stat meant the other stats had to roll low), you couldn't have a maxed out piece of gear outside of very specific edge cases. That's no longer the case - you can get items with all three attributes fully maxed.
- Re-calibration library (you can store high stats to roll onto other gear/weapons later - again, makes putting together builds way more efficient and turns most mediocre builds into good ones while you're still chasing god rolls)
- Harder difficulties on average drops better rolls than lower difficulties, making progression of build/difficulty worthwhile now
- You can now set a Global Difficulty, so everything you do is a certain difficulty/the same level of rewards
- New missions - something like 13 new missions since launch (Tidal Basin/Zoo/Camp White Oak/Pentagon/DARPA Labs/Coney Island x 2 + 5 missions in New York (with more side missions too) and the first raid. The New York ones are exclusive to the expansion.
- Expansion increases level cap to 40.
- Expansion brings you back to New York with more hunters, control points, open world activities etc. and a conclusion to one of the big threads in the Div lore (but honestly, the story sucks, hah). It also brings a feature to keep boosting your character after level 40 by increasing, incrementally, stats such as weapon damage, crit chance, reload speed, skill haste etc. by up to 10-20%. It requires 1,000 level ups to max everything out. So more endgame progression.
- Expansion also brings 3 month seasons that include special bounties, reward tracks (free and paid versions), global modifiers, challenges and time trials, apparel events, etc. that let you unlock rewards. What's nice is that while the rewards are nice, none are exclusive to the season and most of the challenges aren't that time consuming.
Honestly, you'll hear lots of complaints about bugs/difficulty etc., particularly in the Reddit these days. I'd say this - the level 1-40 progression is great and feels super balanced and is a TON of content. After that, honestly, the complaints really only starts to get noticeable/frustrating on Heroic difficulty, and even that I can solo most missions with a couple of different builds. There's some balancing issues at higher difficulties, mainly fire and bleed damage and the accuracy/no damage drop off from SMGs/LMGs/shotguns at a distance that can be frustrating, but it's the first time the game has felt like harder difficulties are actually a challenge so I'll take the hiccups here and there. Also, keep in mind that most of the most vocal complainers of the game were recently rolled back a week of progression/banned for a week for using a damage exploit that made it so that everything was a one shot kill. Hah.