There are some new-ish things, like artifacts that add in new systems or enable different strats- everyone seems to go for the no sprint cooldown, but personally I chose the one that allows me to turn any red bar enemy to my side. Running around with 2-3 Ogres is pretty great! That said, there's not too much that is actually new. Some new weapons and rebalancing, changed end of strike loot, and updated general content (better public event rewards, a new book of achievements to get, etc.). The Archons forge, which a lot of people, myself included, see as the spiritual successor to Court of Oryx, is pretty disappointing. There's a lot wrong with it, but it can be fun if you get a ton of people in there.
For weapon balance, I think everything is pretty good right now. Shotguns are used almost all of the time in the new Supremacy mode, which is annoying, but whatevs. Sidearms are pretty strong, especially for the new exotic one, which seems to spawn you with a bunch of ammo every time you die in PvP. I can't speak for the top 1% of the 1% of PvP players' experience, but I run into a lot of people using a variety of weapons very effectively in PvP.
