I have been in IV rooms on both the Edge and the Beyond, they are exactly the same, however the balcony chairs on the Beyond are now much better than they used to be on the Edge. Our experience on the Beyond was a much better one in an IV than the one on the Edge due to the different climate outside the ship. On our Beyond cruise the climate was cool not much greater than 22 degrees C at any time so it was easier to keep control of the room temperature with window open. Our Edge cruise temperature outside exceeded 30 degrees most days, this will have a huge impact on how people view the rooms.
The ambience of the IV is a light airy space with great views of the sea which we both quite liked, its a pleasant space to be in, thats the pro.
I think a few pictures might illustrate some of the points made, either to enforce or debunk.