Let me begin by saying that I dislike and distrust most philosophy. I didn't always feel this way, but the more philosophy I have read the greater my dislike and distrust for it has grown. The biggest problem I see is that much of it is based in the persisting historical association between subjectivism and anti-realism. This can be traced way back to dualism, when they thought that the mind and body were separate, and even further back to Plato's essentialist ideal forms.
We now know that everything we experience, all our thoughts, feelings, desires and perceptions, is a result of physical stuff happening in our brains. There is no "ghost in the machine", there is no "free will". We cannot choose our experience, it is not something we create out of nothing. We experience what we experience because the universe is the way it is. Just as there are laws governing all physical systems, there are laws governing human experience and, in principal at least, they can be known. Values are facts about which we can have greater or lesser uncertainty.