I refuse to shut up about this game to everyone I ever meet.
I fell in love with it just by watching the gameplay trailers in a way no other 3A title could with their cliche "epic" BGMs.
It has that "old game appeal" but it doesn't have the usual "old game jank".
It features modern mechanics that are way ahead of its time, all with an incredible level of polish.
Everyday I wish for more First Person RPG campaigns like this on the market but my prayers are unanswered.
I bless the day I first watched the trailers, and I thank God for being born in this generation.

This game fits multiple genres.
TPS, PVE, CO-OP, class-based, horde shooter, looter shooter.
These genres do a very good job of summarizing what you should expect from this game.

I'll list a few of my favorite pros, as well as what I think are the most relevant flaws.

Pros:
-1: Not predatory.
You can get nearly every item in the game without spending premium currency.
You don't even need to pay for premium currency, you can get it by trading with other players.
-2: Full Cross-play and Cross-save.
This game is a leading example of full cross-play and cross-save, along with that one popular battle-royale.
-3: Optimized.
Despite having high-end graphics, this game is able to run on Android and handhelds.
Fresh air compared to other games getting released these days...
-4: Customization.
Custominzing characters is pretty fun, even if it does take a while to unlock good mods and color palettes.

Cons:
-1: Challenge is secondary.
When you first try the game, you will notice that enemies barely tickle you, this is mostly because the game is multi-platform and it takes accessibility very seriously.
Doesn't take too long to enter the mid-game, which is challenging, but the late-game is just playing in the background while you listen to something or talk with your friends. The devs already admitted it's nearly impossible to make challenging missions due to the way the end-game power-crept.
-2 : Watered down class-based aspect.
There are now 64 classes/warframes in the game, and yet there are basically zero meaningful synergies that aren't just number increases, and every warrame is perfectly capable of soloing any mission, even if they only excel in one mission type.
-3: Wikislop.
You gotta have the wiki open to see where the stuff you want drops.
-4: Lore.
The game doesn't explain its lore very well. No one understands it and people who say they do are liars. All the characters talk super fancy for no reason, which doesn't help at all.