Warframe has never been released, technically. It's been in a beta since the closed beta began in October of 2012, with the open beta launching on March 25, 2013. Digital Extremes also developed Dark Sector, which shares many similarities and plot points with Warframe and some fans even consider Warframe to be a direct sequel to Dark Sector, with some elements from the game being used in Warframe as part of the background story.
Although Warframe has a fleshed out combat and mission system, as well as a variety of game types and maps, the game has received the brunt of its criticism from its grind-y nature with loot drops and repeating missions, as well as its main story. With the recent changes on mobility and movement mechanics, Digital Extremes decided to overhaul the story to bring it to the same standard they brought the other aspects of Warframe to. The update is titled The Second Dream and "brings a higher fidelity of storytelling to the game in the form of a cinematic-driven quest" which is what many players have felt the game was missing.
In addition to an expansion of the story in the game, a large number of content has been added to keep things fresh for players. Digital Extremes has done this in the form of a brand new Warframe called Ivara, the huntress and the thief.
More of the changes coming to Warframe include the following:
Digital Extremes said:
Warframe: The Second Dream is currently available on PC with a release today on PlayStation 4, with the update on Xbox One "coming soon." Warframe is available to download for free through Steam, or the Xbox and PlayStation stores.
[Source: Digital Extremes Forums]