This is the first game I spent more than 600 hours playing it. It is so additive trying to level up and trying to get all the warframes that you don't realize how much you have spent playing it until you get fat and realize you have spent almost half year playing something that leave you nothing....
I can't say that the game is bad. Actually is very good, well design and great gameplay. The problem is that the only reward you have after playing it is just a lot of warframes and being very powerful by having max out several mods.
This game is "free", but you will spend a lot of time trying to get all you need to move on. You will need slots to keep your weapons and warframes. You will want to keep most of the warframes and weapons after installing them the catalysts and reactors and even with several formas on them.
You can sell things for platinums. The problem is that you need to spend a lot lot lot lot lot of time farming for things to be sold and the spending a lot lot lot lot lot of time trying to selling them at a good planitums to buy slots, catalysts and reactors to be powerful enough to discover all the planets and complete all the tower IV without any issues.
But..... after discovering all the planets, get all the warframes, have a lot of mods max out you started to realize what you have done with your life by playing this game for 6 months, get to rank 12 or 15 and nothing else....
Please, don´t take me wrong. This is a good game. Just take your own conclusion and let me know what you think (if you want to).
Thanks for reading and letting know your thoughts about it.