Roman's guesthouse is a very convenient place to stay in Vienna. Very close to Wien Mitte station! The guesthouse is very clean and there's free coffee everyday! (Illy Capsules). We chose to sleep on the sofa bed and the bed was very comfortable in our opinion. For those who want very soft mattress, then the sofa bed is not for you. The shower is quite small but the strong water made up for it. The guest house was also very clean and well maintained. The toilet is located just outside the unit but this did not bother us. We were told this is typical of an austrian house. Btw, it can get cold inside the guesthouse bec of it's high ceilings and cement walls but there are heaters everywhere should one feel cold.
Overall, we highly recommend this place for those visiting Vienna.