[Gerribase]

In my opinion, practicing Buddhism allows one to have free will. At some level, samsara can be about making the same decision/mistake over and over again (which makes life deterministic), and not always about rebirth/reincarnation. In Buddhism, the source of these mistakes are generally categorized as the 3 poisons (Greed, Anger and Ignorance.) If over the course of your life, you make the same choice at every juncture, the course of your life will be fairly deterministic. If we do not know the precise destination and timing, we will at least know the trajectory.

For example, if a person is always buying things that he cannot afford, then debt and bankruptcy is pretty much pre-determined. This person might think he has the 'free will' to buy or not buy, but in reality, if he cannot control his greed (to buy things that he cannot afford.), the free will is just an illusion.