Finished a four-night stay here. Started my stay a night early given that I was arriving on Tuesday at JNB at 5 AM, but had no problems checking in on the app Monday evening and getting the keys on arrival Tuesday morning. Hotel breakfast is very good - Plat breakfast is continental with a good variety of options, then you can upgrade by adding a hot dish (eg full English, omelette, salmon benedict, etc) for 30 rand/2 USD. Melrose Arch is generally very safe, felt no concerns about walking around at night, although outside the arch wasn't as promising. Service was generally good, although I didn't ask much. Wi-fi was fast.
Minuses? Windows were drafty and not particularly noiseproof, which became a problem when the bar across the street had a huge open-air gathering for the soccer final. Room still wasn't totally finished and sealed, and in the area in the bathroom where there was still some exposure, I often smelled cigarette smoke (either from a nearby room or from a staff nook, I suppose).
Would certainly stay here again if I was returning to Joburg, especially given the points rate here is just 15K/nt.