My partner and I used this as our base whilst we visited Vietnam. When we went on one/two night stay overs in Halong Bay etc. they looked after our extra baggage. It was always a relief to come back to the hotel, because they really do look after you.
They welcomed us at 8am with fruit cocktails at first checked in when we flew in from Europe. We had the room from 8:20am! The rooms were always clean, and surprisingly quiet. The number one thing I have to say is the amazing staff. They were very attentive. ALWAYS trust what they have to say about taxis. The one time we went with a non-Art Hotel booked taxi was the one time we got ripped off. (And they did warn us!)
When we were picked up to go to Halong Bay, we booked via the internet before arriving in Vietnam. The desk staff were very careful to make sure we had the right van, and made sure the driver had proof he was working for the appropriate company etc. etc. Their restaurant reccommendation for down the road (and around the corner a bit) was excellent too.
Breakfasts are free and pretty good, sweet Vietnamese coffee and a lot of egg based breakfasts. (I was sick of egg by the end!) They do amazing fruit drinks!
Great location, the most amazing staff. Ever.