Not all coconut oils have a strong flavor. There are some versions of it that are more processed to remove the strong flavor, and there are some that are minimally processed to that have the stronger aroma and flavor. It should specify it on the label. Some people prefer the oils to be less processed and enjoy the flavor it imparts on their dishes. I don't mind coconut oil personally, it's different from butter, but it has a sweet creaminess in its own right as well. I use it a lot in places where I would previously use butter, such as scrambled eggs or grilled cheese sandwiches and it works fine.
I would be more concerned about the texture of the croissants - if the coconut oil will be able to impart the same airiness to them. I would think it should, off the top of my head, but I've never tried it for those.