The phrase "is rather unclear" is correct and usable in written English.
You can use it when you are trying to express that something is not clear, or when you are having difficulty understanding something. For example: "The instructions for assembling this desk are rather unclear; I'm having difficulty understanding them."
How the government's action in this instance constitutes a "taking" is rather unclear, especially since it was requested by the A.I.G. board in 2008.
Beyond an official insistence that the Socialist party remains a "proscribed organisation", the extent to which the Labour leader still believes in such things is rather unclear: we may soon see, I suppose.
However, the author concludes that this latter effect is rather unclear.
It is rather unclear how inflammation is triggered in the brain, which remains sterile under normal conditions.
Therefore, it is rather unclear whether tools developed for scientific articles perform equally well on patent data.
However, toxicity and risk associated with engineered nanomaterials is rather unclear or not well understood; which is gaining considerable attention and the field of nanotoxicology is evolving promptly.
The images of the smallest 10 nm particles are rather unclear as their size is on the limit of the instrument resolving power.
However, the potential contribution made by the workspace and the physical environment is not fully taken into account because, up to now, it has been rather unclear how aspects of the physical environment, especially light, can support creativity.
Thing is, it's rather unclear why you would want to anonymously connect to a social network that's explicitly designed to track and profile everything its users do.
The ad concludes with Rau stating: "You vote for me, I'll say what I'm going to do, it's going to be clear and I'm going to follow up and do what I say I'm going to do," although by that point it's rather unclear what he has said, or will do, or said he's going to do.
