My impression after read 3 volumes (find the raw by yourself) :
An interesting read.
I'm glad that Ono-sensei adds romance in it. Yes, when I don't have a slightly chance with Jean's unrequited love, that is.
I love the concept, just like Lady and Her Butler.
The oldman is really weird, mysterious and don't really talk much while the lady is an elegant girl. I found it they are very sweet couple.
If you've read ACCA, I think you'll understand. Ono's style is quiet, flat, solid, and the random conversation flow naturally. But I can say that how her manga works is not for everyone. You may be think it is boring. But it worth my time.