We're enjoying the game aswell with my friends. But at the same time, we would probably have enjoyed A16 just as much.
About gun parts, I kinda miss them. Sure, they were a chore to maintain/pickup because of inventory management, but at the end of the day it felt super rewarding to be able to finally assemble a whole gun because you found that last part that you were missing for days. Also, you could upgrade it more and more. I think it had way more possibilities to be expanded, and mods could have just supplemented the old system instead of replacing it. Finding complete guns left and right and having no way to actually make them better overtime is just boring to be honest. At least, even if you found a lvl 100 hunting rifle while yours was already lvl 200, there was a chance one of the parts was actually better than the one in your gun. Right now, you just leave it on the floor because it's useless to pick it up other than to sell it.
But the biggest thing I miss is the schematics. Seriously, being able to unlock virtually everything just by putting points where they are needed is not rewarding in the slightiest ! Nothing will ever bring back that feeling of finding a bookstore because you just knew you were going to improve your crafting capabilities a lot. Now, you just find 30m buffs and mod schematics, it's not even close to the excitement of finding that one blueprint you really wanted for weeks but couldn't find (yes minibike, you know i'm thinking about you !).
I'm also kinda disappointed in the "pure content addition" aspect. There's new stuff but a lot has just been reworked to function differently, we still lack bandits, tamable pets and so forth. Each part of the game has been stretched out to make the road longer to the endgame, but the endgame really isn't that different than A16's, just longer to reach.