I really like the almost "inventory management"-style setup they have for the perks and abilities. I'm one of those crazy people who actually likes that sort of stuff in my games (comes from playing a lot of survival horror and open-world rpg's I guess), so I like that they're going with something a little different than just the standard perk selection that's almost going to require a little puzzle solving in order to fit everything you want in.
And it looks like there are going to be a decent amount of perks and modifiers too. I like the idea of "universal" perks too, reminds me of Dead by Daylight a bit.
I also wonder how many of these new weapons we might end up seeing in the Colonial Marines Operations Manual when it comes out. I see on that Kramer rifle description there's mention of the UPP, so it'd be a nice bit of world-building of some or all of these showed up in that too.