If you played the stress test for Uncharted 4: A Thief’s End over the weekend, you would have played about 20 percent of the multiplayer mode already.
Naughty Dog also mentioned that they previously wanted to lock a certain class to a specific character. They decided against it so players can choose any class they want while still being their favorite character.
The team has not yet decided on what you will get to unlock in the multiplayer mode if you complete the main single player story. As of right now, many of the unlockables you get are earned via the multiplayer mode only.
The latest stress test is also not the latest build of the game. Naughty Dog noted they have made several changes since then so the full game’s multiplayer mode should feel a little more different.
Uncharted 4: A Thief’s End comes out on May 10th, 2016 exclusively for the PS4. It was delayed by two weeks in order for Sony to manufacture enough copies to meet its high demand.