For me I rank it just after WaW, which for me is tied 3rd with MW2 but for most people would be ranked 6th lol.
The best way I would describe it is different.It doesnt play much like any other in the modern era CoDs. That my opinion, but its also the reason I actually like it (hated BO1 and rank that second last in the entire series after CoD3).
Perks no longer feel neccessary, which some people call balanced.
I feel that a little bit more could have been done to make some of them feel like a viable option. Teir 2 has no standout useful perks and most my classes do not have one equiped.
Hardline (Teir1) and seing equipment through walls (forget name, Teir3) are the only perks that are notable enough for me to use regularly.
There is leadway in this though as it leaves you open to make the choice of adding something different to your class. Once you start thinking outside the box and remove yourself from the old idea of how your class is created you can come up with some extremely fun classes to play.
The map design is continuing the BO and forward idea of not having any less than 2 or more entrances to an area. Forcing movement and increasing the chances of enemy encounters.
There is once again the lack of even a single sniper map which makes me greatly sad. There are areas on some maps that are viable for sniping, however when that area is the main part of the map (looking at you Drone), its pretty much impossible not to get counter sniped). Just a single map in the vein of Wasteland, Overgrown, Creek, Downfall, Outskirts, SEELOW! I would be greatful for. Even if it is going to be skipped over 90% of the time, just the option would be nice. However I can accept that CoD is no longer the game that provides that experience (I belive this is mostly due to the criticism WaW recieved), but I degress.
Gun choice doesn't feel relevant outside of choosing gun class and rate of fire, another issue I have had with the series since BO1. A gun is a gun and is going to kill in a couple of shots,
New additions of things such as Black Hat are fun and open up different play styles. My traditional sniper class always, without a doubt has been Sniper + handgun leaving me open to airsupport attacks. Blackhat, being an equipment means you can still have the fun of messing with people's pointstreaks and not jepordise your CQC safety.
The Assult Shield a good fun and alot more versitile than the riot shield. Get to the objective, place it down, pull out your secondary and defend from cover. Had alot of fun experimenting with that class today.
I'm sure I could go on for ever about the game but really my only point is that its different. Its the same CoD, but tweaked to be something not quite what it was before. Mostly in a possitive way.