My husband and I went to Newport for a relaxing weekend and we got it. The Mariner house is a lovely B&B and Sharon the owner is a very nice and helpful woman. When we arrived Sharon directed us to an off street parking spot so we wouldn't be ticketed she then gave us a tour of the house. As many other reviews note, there are a LOT of teddy bears. I don't care one way or another for stuffed animals, but Sharon loves them and they are her 'thing' and I found it sweet how she had stories about where they came from. They are all over the common spaces, but it's fine since you will spend most of your time outside and not in the house.
We had a room with a private bath. Both the bedroom and bath were spotless. The room was pretty comfortable with room to spread out a bit. There was an AC which we didn't need to use, but I would have liked to open the windows to get a breeze in the afternoon, but I couldn't figure out how to keep them open (this may have been a problem with me and old windows, not the window itself). We slept pretty comfortably on the bed, but it did creak a bit so we just slept.
The house is within 5 min walk to the top of the wharfs and we walked everywhere. There was so much to do and Sharon really knows her attractions and will give you all sorts of information. If you take the time to chat with her for a bit you will learn so much about the area, the history of the house and all sorts of things you can do during your stay. Just a note, she can have long winded stories in the morning which do annoy some people. I didn't mind at all since my family is like that too and I'm used to it.
If you plan to visit Newport and want a mid- to low-priced place to stay that is close to everything where you will be out most of the time, I would recommend the Mariner. If you want a place that you can hang out in the B&B much of the time in quiet, find some place else. There is some outdoor space to hang out, but that's about it, and you will likely get caught up in a conversation with Sharon (which is not a bad thing I think).