Warframe has a lot of interesting and creative shooter-gameplay mechanics which are spoiled by a vicious business model for long term progression. The fundamental design of the game revolves around abusing addiction and heavy time sinks, which is an especially dangerous combination for vulnerable populations. One of the consequences of this model is that the core appeal of the game switches gradually away from the experience quality towards virtual currencies and items, reducing the time spent in-game down to mindless repetition.
Warframe can still be a satisfying and beautiful experience if played responsibly and in moderation. However, by merit of the existence of better, less predatory shooters, it is best passed up. This should be avoided at all costs by people with addiction-prone personalities.