I still have not played this. Any good? I've heard meh things from my buddies.
The game has a lot of issues. It can get very laggy, glitchy, grindy, repetitive after a certain amount of time. But the biggest problem with the game is the limitation of everything basically. Warframes have two slots free, weapons have eight (?) slots free. The game wants you to spend real money or spend so much time grinding and trading with other players for Platinum which are in games' second currency.
Let me give you an example, if you have two Waframes crafted, you can't craft another one unless you sell one of your Warframes or buy a Warframe with Platinum which you can purchase with real money, however if you do, you'll get an extra slot and a reactor. The same applies to weapons. I don't mind spending money, in fact I supported them but the problem is it's too expensive for the options available.
Another problem the game has, it's very confusing for beginners to get into. It isn't just shoot and kill. The game has an RPG like element which you have to do Maths (of course there are Wikis out there) in order to get your damage up. It isn't an issue if for the fact some of the Mods have a rare drop and in order to get these rare Mods you have to be strong enough to clear certain missions or defend the objectives. Sometimes even if you get the Mod you want, if the Host quits, random disconnecting from game or any other problem, you'll loose the Mod which gets very very very very annoying since you need to be pretty strong before you go to higher level planets and the fact Mods drop randomly. I'm a Shotgun user and I still have yet to get any Mod apart from one Damage Mod that does anything good and I've been playing it for more than 40hrs+. You're off better with Rifles until you get other Mods but you could always be lucky since the Mods are random in certain missions.
Outside of the game, it gives you a variety enemies and planets. But overall, it's a very fun game especially with friends.
tl;dr: The game has a lot of issues but it's still very fun.
Pro tip: Try to get the Warframe ''Rhino'' if you like to rush in and be a tank.