Abu Dhabi is a reasonable choice as they filmed the original trilogy Tattooine scenes in Tunisia. It gives them a very similar look and is not necessarily more expensive to shoot at as it has modern airports and support facilities right at hand.
If they can judiciously use location filming to prevent the film from being an over-CGIed abomination then good for them.
That does not answer the question. The deserts in Tunisia do not look different than the deserts of the Gobi, the Mojave, the Sahara or any other desert. Location shots in cities and other known locales cannot be substituted, but to say that this is okay because they shot the Trilogy in Tunisia still does not make sense. It is like saying that 100 square miles of the Atlantic ocean are different than 100 square miles of the Pacific Ocean or the Sea of China or the Gulf of Mexico.
The film is going to be substantially CGI because it just isn't financially feasible to do it any other way. I think if you are hoping for real sets, you are in for a big disappointment. Maybe one large interior and maybe a few generic exteriors, but most of it is going to be composites CGI.