When I got my PS4 I was so excited to finally get my hands on games like Killzone Shadow Fall or Battlefield 4. When I saw Warframe in the PSN store and noticed that it was Free To Play I decided to give it a go, too.
Boy what a surprise! I cannot really say why but this game has me hooked really bad :) ! The graphics are great, the action is awesome and the hunt for more resources to craft/get new weapons and mods is immensely satisfying.
Since downloading Warframe I did not play any other game on any other platform (PS3, PC etc.). So far I have spent about 25 hours with the game, which is probably next to nothing, but it still excites me tremendously.
To have real fun right away you most likely have to spend some real cash though. The 3 warframes (classes) you can choose from in the beginning are not bad, but most players probably want to select one of the other warframes, which can either be obtained by farming or by spending some real cash.
All in all, this game is awesome and should definitely not be ignored... especially since you do not have to pay anything to test it!