Stayed at Novotel Athens recently and overall it was an average experience. The location is fine. Walkable to metro stations, which made getting around easy, though it felt a little unsafe after dark.
Breakfast was extremely busy, often with nowhere to sit, and the food itself was just ok, nothing special. The pool was small and packed with kids, some using flippers and pool toys, which made it hard to actually relax and enjoy.
Being a large hotel, noise was an issue too. You could hear other guests both at night and in the morning. For the price they charge, I expected a bit more overall.