Mari's place is a good spot to start your adeventures in Riga. From it, it is easy to reach all of Riga.
The place itself is clean and spacious and if you want to get of the streets and just relax a second it is possible to do that.
Also staying with Mari is easy and works wonderful. She is a gracious host that answered every question I could find within seconds.
One thing one should be aware of though is that the place itself is situated right at one of the main streets of Riga. Therefore if you are sensitiv to noise it might not be for you. Also you should be fine with some tremors. Due to cars driving outside it can be that the apartment is slightly shacking from time to time.