This is believed to be the last chance for people to try it before they split Star Citizen and Squadron 42 into different games and start selling the separately.
If you are looking into getting into Star Citizen I would get it now while you can still get both games for one low price.
The free fly trial will give anyone with an account regardless if you bought the game or not a chance to enter Arena Commander or the universe and fly around. You just have to create an account to try it.
If you are feeling thoughtful and decide to buy the game you can use My referral link to give yourself a free 5,000 EUC (in game credits) and give myself some goodies.
Edit, I will not be commenting on any Star Citizen hate replies so don't bother.