It's behind Corvin Plaza in the 8th District, on one of the most jazzy and vivid locations. The apartment I was in was O.K. but be aware, you should pay for everything. For instance, 5 Euros for a remote control to switch on the air conditioner/day, 20 Euros deposit, cleaning, WiFi sometimes horrible. When I complained about the rip-off to a guy at the reception desk, he was absolutely ignorant and impolite. Very bad experience.
As much as Sun apartments look excellent and in good shape, the hospitality and service is disappointing.