I have seen these cabins when they were the R Ships with Renaissance and on the Azamara Journey.
The size is OK but not large. I think around 150 - 160 sq. ft. The obstructed view cabins on deck 6 have a larger window and depending on the cabin will not have an obstruction but a life boat on each side. They are also parallel to the hallway instead of being perpendicular to it. This gives a feeling of the cabin being small when you first walk in but once you are in that feeling goes away.
Actually, none of the cabins on the former R ships are huge. The suites are a good size, especially the top end aft and forward suites but the balconies are 165 sq. ft. and the insides are around 150. All of the cabins make an excellent use of available space and I never felt cramped. I had a similar 165 sq. ft. cabin on Dawn Princess and I felt cramped because of the layout.
If I had to book a cabin on a former R ship, like Quest, I would take the ones on deck 6. Others may have a different opinion.
Take care and enjoy Azamara. You will enjoy it no matter what cabin you choose.