Warframe is a cool game with a lot of problems. Its got a ton of different weapons, and a lot of different characters you can use with them. The movement and shooting are pretty cool and satisfying, but there are some issues. Most guns function in their own cool special ways, and the modding system for weapons pretty much lets you make it your own with whatever you want to do stat wise. The problem is that you end up kinda getting pushed to whatever's optimal, cause eventually enemies become harder to kill without something good, like most games I guess. A lot of the bosses are either damage sponge DPS races (with heavily damaging attacks that are incredibly difficult to dodge), or they're damage sponges with one specific weak spot and hitting them anywhere else doesn't do damage. The game has cool movement with wallruns, wall climbing, doublejumps, and slides. Using these is pretty nice but there are a lot of times when it won't work how you want and it'll suck. Also melee weapons in this game have very little feedback when you're hitting stuff, even with most weapons' charged attacks. There are blocks and counters with the melee weapons but they really don't feel like they're there.
I think the biggest issue comes down to how the f2p system works, cause its gross. Its nice in that, you can get pretty much anything you want without spending money, you just have to invest time and effort instead of cash. You can even get the premium moneybucks without paying money if you get it from other players. The crafting system is great because it lets you feel like you're playing a scummy mobile game instead of a cool third person action game. To craft something you need a blueprint and materials, once you have both of those you spend the materials on the blueprint, and then both things disappear (unless its a fancy blueprint) and after a certain amount of real-life time elapses you get your thingy. Small things will usually be instantaneous, weapons and important crafting things will take 12/24 hours to complete, but you have the option of spending real money to finish it instantly. You can't just go to an in-game store and buy a gun you want without real money. Say for example you want a shotgun- you can go to the store and buy the blueprint with in-game money, then spend materials to make the blueprint and in about a day you get your shotgun. Every warframe and most fancy weapons require several blueprints (Warframes need 4, the blueprint for the warframe, then the systems, optics, and chassis. You build the last three separately and then combine them into the first.) and since the blueprints to build these things are almost always random drops from missions and bosses you do a lot of the same mission over and over until you get it, and then you go somewhere else for the materials you need to build it. The issue is that you have a limited number of warframe and weapon slots that you can only expand with real money, so the game kinda encourages making a thing, getting it to max level, and then deleting it and moving onto a new thing because in order to level up as a player and continue the story and gain access to other stuff, you need to level up weapons and warframes and after you reach the cap with one weapon, you get nothing for leveling up the same weapon. Missions that have a chance of dropping something you want will a lot of time time require you to craft a key to get into the mission, which takes time and resources, and even then you're at the mercy of rng which decides whether or not you get to spend another hour crafting a new key, just so you can get the blueprint you want to spend more time crafting a thing that lets you spend more time crafting the thing that gives you a cool gameplay thing.
Archwing missions suck and are zero fun to control, stealth missions are cool but they rely on platforming, and if you try to do them with randos someone will trip the alarm and you get to fail the mission and start over sometimes. Survival missions are fun and offer a challenge that ramps up over time, the main issue with them is if you want rewards from them, because the rewards you want will only show up at 20/30 minute marks of survival, and yet again the thing you get is tied to RNG so depending on how lucky you are you get to do the same mission for half an hour again.
For a f2p game it is very pretty, everything has a cool and unique appearance, your customization options are pretty nice, there are some nice butts. The f2p system is complete garbage and if you're a compulsive completionist or collector the game sucks you dry from either your will or your wallet.