Karim’s place was extremely convenient, close to the train station and close to Place Dorciere (if you want to take a bus to Chamonix). It was also easy to walk to the water front and any shopping. The place itself is simple but has everything you need. Checkin was very simple and straightforward.
The only concern I would share is the walls are pretty thin. If you are light sleeper, it’s easy to hear people next door or in the hall. For the most part this wasn’t a huge problem but it did wake us up a couple times.