I know I'm replying to an old post, but I was looking to see if there was any PS4 Warframe discussion around these parts. Let me say tho, the game is NOT a "cash grab" or a "pay to win" or whatever. You can buy frames & weapons, but that's more of a way to pay to circumvent playing the game (which has always seemed silly to me), plus those things won't really make you powerful. Getting mods that drop in-game and leveling those up is what really makes you stronger. The game is best compared to PSO - imagine if PSO were crossed with a 3rd person shooter with a bit of a collectible card game thrown in. There's a ridiculous amount of depth to the game and it's an absolute blast to play - I probably have somewhere in the neighborhood of 150 hours clocked in so far.
The only real knock against the game imo is that it does a very poor job of teaching you how to play. So that means you have to put some effort into digging into it and probably reading up some on the 'net. But again, if you're a fan of PSO it's well worth it.