The motivation for compatibilism is to allow for moral praise and blame. If our actions are determined, it is difficult to see how we can be held responsible for them. Hard determinism accepts this and rejects moral responsibility. Libertarianism (NOT the political position) also accepts this and accepts moral responsibility. But if we are free to do what we want, then we can still say we are responsible for our actions, and so moral praise and blame is possible. Supposedly.
Peter Van Inwagen is one of the most important living philosophers. He earned his Ph.D. in 1969 and has began publishing on determinism and free will ever since. Eleven years into his academic career he converted to Christianity, which is interesting but unrelated to what I'm talking about. He also came up with the Consequence Argument which is essentially an argument against compatibilism. It argues that the free will of compatibilism does not allow for moral praise or blame, moral responsibility, and this takes away any motive for accepting compatibilism in the first place. We should either be hard determinists or libertarians.
The argument in a nutshell: if determinism is true, all of our actions are entirely produced by events in the remote past plus the laws of nature. But we have no control over events in the remote past or the laws of nature. Therefore, we have no control over our actions. If we have no control over our actions, we are not responsible for them, in which case praising us for our good acts and blaming us for our bad acts makes no sense.
Van Inwagen affirms free will, but also points out that it is a mystery. It has yet to be made into a coherent idea, despite the facts that we have an intuitive understanding of it and it has been something people have been discussing for as long as there's been people. Simply saying our actions are not determined is not enough, since we could hardly be held responsible for actions that just occurred spontaneously with no cause. Nicholas Rescher, another Christian philosopher and probably the most influential philosopher of science after C.S. Peirce and Karl Popper, published Free Will: An Extensive Bibliography, which is exactly what it says it is: over 300 pages of references. So I don't think the issue is going to be resolved anytime soon.