Good location. UBahn line 4 is only a few minutes walk. From here, you can go one stop to Karlplatz, where the Opera House is. This is a major corner where you can transfer to both U1 and U3 lines. One stop to the north here is St. Stephens. The Opera House is also the meeting point for the Hop on Hop off buses that work with those using the Vienna Pass and those who want to ride the buses around.
Room is fairly basic. Would not recommend for more than 3 people and toilet situation is quite intimate as it is basically in a closet right next to the bed. Directions can be confusing, especially to someone picking you up or dropping you off. Apartment is divided into 4 units, each with own security code, so those in other units cannot access yours. Code system can take a couple of tries, so be patient!