A review in two parts:
First, the location was absolutely perfect. Right on the river, and 4th floor so amazing views out the VERY large front windows. Watching the boats go past and seeing the cathedral and basilica lit up at night is just incredible. It's also just a few minutes walk to the Old Town (just across the pedestrian bridge which is 100 feet from his front door). And a fantastic bakery on the next block for fresh breakfast every day. The apartment is also quite large so you didn't feel cramped at all. Multiple grocery stores just a short walk, and 10 minutes will take you to the central square and many cafes/brasseries and the other river. I can't say enough good things about where this place is. But...
This is the owner's ACTUAL house. As in he lives there full-time with his family the way these type of rentals used to be. So all the family's stuff is there. All their clothes, toys, games, books, and everything else just like anyone's normal house. So there isn't really any room to hang up your stuff, or put things away. This also means there are no toiletries or dish soap (that we could find) of any sort for you to use so you have to bring your own. It also means that even though it's clean, you still might find, for instance, used tissues in the couch cushions, or a pair of dirty underwear down the side of one of the beds. This is NOT the type of home rental that most people are probably used to these days where it's almost like a hotel. And there is ONE toilet. There is ONE shower (and a bath with a flexible shower hose) so bear that in mind depending on the number of guests you have. And there's no other way to put it, it is VERY noisy. The floors squeak loudly with every step. Every. Single. Step. The doors have to be closed with force so it sounds like they're constantly being slammed. And maybe it was just because the weekend, but there were literally fights and shouting at 3am in the alley behind the building every night so if your room was on that side, well that didn't help. No AC so with the windows open we heard it all. At 3am.
The owner was VERY responsive, and there was a garage around the corner we could use so that helped. So in short, the location was absolutely perfect, but you have to expect the above conditions as well if you rent.