I spent one night at the Hotel de la Cite in a double with sea view for single use.

I decided to pay extra for a sea-view room in the old town because I wanted to see low tide during my short stay in St. Malo (and low tide was in the middle of the night) and I also wanted easy access to the walls for high tide, which began shortly after I expected to (and did) reach the city. My room had a tiny balcony from which I could see the sea, as well as something that was an island at high tide, but was not at low tide. Cool! I must admit that I was, at first, a bit disappointed that I had to step out on the tiny balcony and look to my left to see the sea, but when I later walked the wall, I realized that it was actually a decided advantage, because it meant that none of the many people walking the walls could see into my room. (During my walk, I saw many rooms that do not offer privacy, so if that matters to you, check in advance with your hotel, whether the Hotel de la Cite or not.)

Other aspects of my experience at the Hotel de la Cite were less enjoyable:
(1) The bathroom was, in some ways, nicely appointed, but it did not serve my needs well: (a) There wasn’t a place for me to hang handwash to dry. (b) The shower area was in a bathtub and was “protected” by a panel that extended only about 2/3 of the way along the rim, making it difficult to prevent water from spraying into the bathroom. (c) There were two ways to shower: 1st, by a direct overhead spray (which I strongly dislike – I want an angled spray, not one that beats directly down on me), or 2nd, by a nozzle that was housed at waist height and could not be used for hands-free showering above that height, which is far lower than I prefer. Maybe these options suit others; I strongly prefer a hand-held fixture that provides an angled spray and that can be anchored above my head.
(2) It was noisy when I was there. For one thing, there was lively bar with outdoor tables a half block away that was open until 3 a.m. For another thing, a large group of German tourists was staying at the hotel when I was there. I could hear their voices from my room well into the night and then again early in the morning, and the breakfast room seemed to echo with their efforts to shout over each other. I don’t mean to criticize these other visitors to St. Malo – I hope they enjoyed their stay! And I realize that there is a limit to what hotels can do to protect their residents from certain sounds. Nonetheless, I was disturbed by the limits to the hotel’s soundproofing.
(3) The color scheme in my room was a strange and discordant combination of lavender walls, pink and pink striped sheets, intensely yellow curtains, and silver-metallic walls. Time to redecorate!

(4) Finally, the breakfast buffet included delicious unfilled crepes dusted with powdered sugar, but otherwise struck me as offering a more meager selection than comparably priced buffets.

If it weren’t for the view, I would have thought this hotel outrageously overpriced for what I got. I don’t regret my decision – from what I could tell before booking, that this hotel’s sea-view rooms were among the least expensive in the old city, and being able to see the island that was only sometimes an island from my room was definitely nice. I don’t know whether other hotels offer a similar view, or whether one can get a better sea view for a more affordable price elsewhere in St. Malo. In the absence of that information, all I can say is that if you are willing to pay a pretty penny for a sea view, are confident that you will have an adequate level of privacy (I don’t think that all the hotel’s rooms provide the side view that mine did), and are willing to put up with some potentially problematic or unpleasant elements, the Hotel de la Cite might suit you.