The apartment is fully equipped. Besides some usual things like air conditioner, there are some really nice bonuses: a washing machine and detergent, a fridge with water filter and ice maker (no need to wait for it, ice cubes are 1 button away!), all kinds of dishes and utensils. Almost every piece of equipment has nice and clear usage directions in English. Check-in process is really smooth and incredibly fast, everything is thought-out really carefully! There's also a lovely balcony with a table and 2 chairs that could make home-cooked dinner even better! Internet connection is good (downstream is about 10 Megabits/sec as far as I remember)
The location is also perfect. It's easy to get there from metro (maybe 5..7 minutes from the nearest station or so) and it's easy to get from there to all main attractions. During 2 days of sightseeing we haven't used public transport at all -- not even once. It's half an our of walking (tops) from almost everything. I would also recommend Sklavenitis supermarket that is only one block away.
I love objective reviews, and one without any downsides usually looks suspicious. Believe it or not, it was really hard to find anything that isn't perfect. Still, there's one thing that is just 'good enough'. Bathroom has a rather low ceiling. It was totally OK for me and my wife as we're not too tall, but a person taller than 175 cm (5'9") probably won't be able to use all the parts of the shower (it has 3 taps: one is fixed at the top at ~175 cm, another is fixed on the side and the third one is detachable) and one who's taller than ~185 cm (6'1") will likely need to bend a neck to take a shower (ceiling is about this high above the bath bottom). It was a non-issue for us, but might be for someone, so it's worth knowing.
In the end, I would like to thank Tia for an absolutely lovely stay. I will definitely return to the blue room (or a golden one in the same apartment) if I happen to be in Athens again. Keep up the good work!