All the reviews are true - Aristotelis is amazing - waited hours for us because of a strike that paralyzed the city, and then carried our bags up the hill from the Monastiraki metro.
The place was indeed extremely clean, like brand new, and full of everything you'd need, including food and drinks.
Location cannot be beat. There is no washer/dryer but no worries, there are several cleaners/dry cleaners within a block (I liked the one across the street) and they are fast and cheap to do a whole suitcase full of clothing.
Internet works great but could be faster. Great Airco.
Only potential negative - it does get pretty lively in the neighborhood on Friday and Saturday night (other nights and daytime, quiet). Didn't bother us, but I'd recommend earplugs if you are a sensitive sleeper.