We stayed here in mid June for 9 days after finishing a river cruise. It's a great apartment just off Vaci Utca. It has a fully equipped modern kitchen (which we we really didn't use because it was so inexpensive to eat out). It's within walking distance to the Great Market Hall, the Danube, Gellért Baths, heaps of restaurants and cafes. It's also close to public transport if you want to travel further.
The apartment doesn't have air conditioning but that isn't an issue, it was 38°C and the apartment stayed comfortably cool.
The only thing I would have to mention is the shower in the bath. We had no problems using it but it could be a problem for some people getting into it. The sides of the bath are quite steep.
We highly recommend this apartment, if you want to stay in a spacious, fully equipped apartment in Budapest, this is the place. Plus it is also very reasonably priced.
PS (Don't dine in Vaci Utca where they spruik, turn left when you walk out the front door...