The location to the republique metro station is great, the 5 lines from it take you directly almost anywhere you need! Going to a tourism office (in the north or west train station, within walking distance) and getting a metro map straight off is a good idea. Also at the tourism office you can get a 2,4,6 day Paris museum pass, or admission passes to any museums. We found that helpful too. At the metro we bought 2 carnets (carnays) of metro tickets and that lasted a whole week. 10 passes per carnet, for 14,50€, saves a few euros. We enjoyed touring all the tourists spots, but preferred the Belleville and Goncourt neighbourhood behind the flat, much less touristy and more real. And cheaper.
The handheld shower took a little getting used to, and the place needed a bit of a clean for sure, but the location, the helpful-ness of Olivier, and having an elevator were all so great!!!
Also there is 1 grocery market on either end of the block, and tabaco and donar shops across the street. Handy!
Also, I HIGHLY recommend the app maps.me for offline navigation! We could see exactly where we were and chart a route to where we wanted to go at any time with no wifi or data necessary. I don't know how we could have done paris without it. :)