I had one before my 5th and we really liked it. On our 19' Antigua the screen room basically doubled the living space. Our kids were very young at the time and the screen room allowed us to have them go to bed, while we enjoyed the evening outside. We also had privacy panels so it was truly another room.
One option which we had and is no longer available is a hard door option. This was a storable storm door which allows you to come and go without using the zipper.
I would have kept the screen room, but the 5th has an electric awning, and the room I had wouldn't work and we really didn't need to have the space any more. We now have a standalone screen enclosure although we don't like it as much as the screen room.
They are a little cumbersome to setup and take down, especially in the rain, and for a short weekend stay we wouldn't put it up. Anything more than 3 days and we did. Hope that helps.