We stayed in the one bedroom apartment for a week with our 6 month old baby, and really loved the place. The apartment is very spacious, which is important when coming with kids and all their equipment. So much more comfortable and practical than a small hotel room. The kitchen is well equipped with everything you need, and in general the design is very clean and modern. Room cleaning is available on demand, so we requested it every other day and the results were great. Also you can request drinking water to your room whenever you need it. There is even a washer and dryer available for free for guests, though we ended up not needing it.
We were worried it would be noisy, but due to good insulation, the apartment is very quiet at all times.
The reception operators were very nice and helpful, doing their best to assist us, even with problems during the night shift.
Breakfast remains pretty similar each day, but it's a nice selection (though the hot dishes weren't always very hot) even for those that don't eat meat - they made us our own eggs benedict each morning without the meat it is served with.
The location of the hotel is amazing, walking distance to most areas you want to visit, and near the metro and tram lines to take you anywhere else (even with a baby) - and yet the hotel itself is on a more quiet street, out of the hassle.
To sum up, we highly recommend staying at OREA Place Seno, and coming to Prague in general!