The location is good, opposite the Ares Park, and a convenient distance to the Metro station at Victoria.
I use Radisson quite a bit as i find all their hotels to be at least acceptable. This one was possibly the best, even better than Reykjavik.
I found the staff to be particularly friendly, from reception (thank you Niki) to the bar and restaurant.
The room I had was very comfortable and had a balcony, which I only used for photography (I could see the Acropolis, barely.)
I was very impressed by the food offering. Normally I avoid hotel food as it's pretty average at best, but this was good, and i ate there for two nights. The views of the Acropolis from the restaurant are excellent. As Athens is a low rise city, and this hotel has 8 floors ( where the pool, bar, restaurant etc is located), you're guaranteed good views.
What wasn't so good? Wine and beer selection, in common with many places (not Just Greece) was uninspiring.
In the UK, we've lost so many good people in hospitality due to the idiocy of Brexit , it's good to be somewhere where service still matters