I read the reviews and everyone else was right. It's a "guest house" located outside the city center. Most taxi drivers did not know it, so I had to have the address written to show them. The service staff are excellent, the room was beautiful (we stayed in the big room on the top floor - big, spacious, very nice). Breakfast was good, staff was accommodating and helpful and gave us everything we asked for.
I hate to say anything bad because the people were so nice, but the location of this hotel just isn't convenient. I had stayed in the Hotel Rus the week before, and the location of it was good - they had a bar, restaurant, ATM machines, money change service, concierge, taxi service on-site and it was with a short walk to downtown Kiev. But the rooms were very small.
So, if you prefer a more home-style environment, if a nice room and friendly staff and don't mind taking a taxi every time you need to go somewhere, Oselya is great.
If you prefer more services inside the hotel (restaurant, bar, club, etc), or if you want to be more centrally located, Oselya won't be the best choice.