It takes a while to get used to, but it really feels like COD MW2 (naturally). Ya, you die a lot quicker here, but idk - I feel like I can shoot someone for ages but they never die.
Ballistic Vest perk in the support streaks is a great way to EXP and level up, btw. And who doesn't love a good ballistic vest?! I do love support streaks since in long matches, you're almost guaranteed to get Stealth Bomber and that final one (Osprey with a different name...).
The "proficiencies" is what Mike is talking about. You can literally have Sleight of Hand, Assassin (which is like ghost), and a third perk (I like Marksman a lot!), and then do 2 weapon attachments as your proficiency which is going to be amazing in my opinion for how I play!
I'm not level 20 yet, but once you get there you can do "Specialist" kill streaks which is basically:
2 kills = 1 extra first perk
4 kills = 1 extra second perk
6 kills = 1 extra third perk
Pretty perk-friendly!