Homm is a business, not a family or individual host. So you really get the sense that you're just a number to them, not a guest that they care about. There are so many great value places to stay in Athens that I wouldn't recommend Homm.
I'll start with the good: this place is extremely central, and you're within minutes walking distance of everything. You have pretty much everything you need for a few days in Athens within the apartment, and the check-in was efficient and helpful. It can be noisy so bring earplugs if you're a light sleeper.
But they didn't really care about customer service. This became most apparent during check-out. We asked Homm if we could store our luggage with them after we checked out, and they couldn't confirm until the day before. But the main issue was when we did check out - the receptionist told us to leave our bags on the street until he finished cleaning the reception. I'm not sure why he chose to do this at the hour of check-out. When I said I felt nervous about leaving my bag on the street (which is fair given how many pickpockets there are in Athens), he became very rude and angry and said "If you don't trust me, that's your choice!". I calmly explained that I did trust him (otherwise I wouldn't ask to leave my bags with him), I just didn't trust the street. He then told us to go somewhere else if we weren't happy with his solution, which we did - we paid about 10 euros to a lovely family-owned locker business next to the Metro station. I sent Homm a message to let them know about the situation, but their only reply was "sorry about that".
In a nutshell, Homm doesn't really care about their customers, and I'd recommend staying at a hotel or a family-owned Airbnb with a similar location and price point.