My wife and I really enjoyed Magnus' place. We spent nearly two weeks here. A minutes walk to the metro station and tram lines that will connect you to anywhere you want to go in Prague. There are great dining options within walking distance as well.
The apartment is very spacious and quiet. We made use of the enormous projection screen to catch some of the 2018 Winter Games coverage. The internet speed isn't great (I had to do some work remotely during our stay), but on par with every other place we stayed at in the Czech Republic, so I don't think this issue is unique to Magnus' place.
Magnus is also very responsive. The only issue we encountered involved the heating failure. Luckily, we had planned an overnight stay that coincided with the issue, so we weren't affected. Magnus immediately responded and had a repair person come out while we were gone, thereby resolving our issue.
All told, I would recommend staying at Magnus' place to anyone spending any amount of time in Prague.