Many thanks to Katka for the great apartment for my parents' vacation and also thanks for invitation letter for mom's visa.
My father's review:
Apartments are located on the 6th floor of rather big building with elevator. The neighbourhood is clean and placid, nevertheless is quite close to the main attaractions of Prague: Old Town, Charles Bridge and Grad - we didn't use transport to get there (however, it depends on a tourist's mobility and will as well as a load). Nearby apartments (5-7 minutes by foot) there's a big commercial center stuffed with all for shopping (e.g., TESCO supermarket) to say nothing about plenty of more small shops and various eateries. The appartments itself are spacious for two, bright and immaculately clean. All you need for comfortable staying you can find there: flat TV, stereo music center, plenty of home appliance and quite reliable WiFi connection. The owners (Katka and Robert) are very attentive, tactful and friendly. All in all, Prague is absolutely worth every penny to pay for. The appartments are highly recommended.