We stayed here in October 2012 for two nights in a Junior Suite on the 7th Floor. Location is good but is pricey. Service from staff was good. Used the clothes dryer that was on our floor a couple of times which was quite handy. Room itself was very clean and well presented. Bathroom was large and the shower excellent. We had a king size bed and the kids a pull out sofa bed which was really too small to accommodate 2 kids so one ended up sleeping on the floor using the sofa cushions as a mattress. Had one issue with the tv losing reception but the was promptly fixed by maintenance.

Overall a good experience and I would stay here again but select a different room as the sofa bed was only large enough for one.

CHECKIN was very good .i would say Robert was outstanding and groomed in true marriott style,location is excellent. but rooms are very small and beds are very small. i think marriott needs to recheck the size of beds and hotel rooms .walls between the rooms are thin and you can hear the sounds from a adjoining room .bathroom was small and not so good.i would say that you should look for other hotels in union square.

After having read the reviews for the Marriott Union Square I wasn´t sure whether I should book it or not as some of the feedback was very mixed. But due to the Iphone 5 release a lot of other hotels were booked and I wanted to stay central.

On the positive side:
The hotel is ideally located for a city and shopping trip to San Francisco.
We took the BART to Powell Street underestimating the steep hills of SF - but we managed to drag our luggage up to the Marriott.
Union Square is just a minute away and a Starbucks as well as a diner is just across the street in case you want to have breakfast elsewhere. Also the cable car turning point Powell Street is close as is a cable car stop on the next corner. China town and several restaurants are in close walking distance.
We stayed in one of the refurbished rooms on the 28th floor (2815) and during weekdays a continental breakfast was included. The room was spacious and clean and quite quiet. Even with open windows it was not too loud as we were so high up but you obviously heard the police sirens.
The room included bathrobes, an iron & ironing board, a hairdryer, a safe and a coffee maker. The room and bath were cleaned thoroughly every day and the bed was very comfy.
The continental breakfast is located in a seperate room on the 28th floor and offered a good variety if you are not too much in to English breakfast with eggs and sausages.

Which leads to the negative:
The breakfast room can only be opened with your room card to be held against a not obviously placed card reader. We were not the only guests rattling at the door as no signs indicate how to open it. But instead of service staff one of the other guests helped us out. Breakfast is a buffett so you have to help yourself which is fine if everything is available and refilled. Unfortunately that was not the case. Staff was not very attentive and only refilled on request. Plates and glasses were partially dirty and I had to dig out a clean cup myself.
When addressing staff and raising this I felt as if I was disturbing them - they were not outright rude but very indifferent and hardly reacted - and did nothing!
Same was valid for most reception staff: When asking for advise on where to eat out or for directions most were indifferent and one was outright rude. One reception lady though was a single light of friendliness in an otherwise dark sea of rudeness.
Another downside was the WIFI which you had to pay for which I would expect to be included in such a hotel. Also WIFI reception in the room was quite poor as was the speed.

Nonetheless I would recommend this hotel for a shopping and sightseeing visit if you can book a refurbished room on one of the upper floors AND given you are not too fuzzy about good service. Also you should eat breakfast elsewhere which should be easy in such a central location.

Yes, the location just off Union Square is really good, but there are so many great hotels in this area that it takes more than location to make me return. And this hotel does not have it. We had problem after problem at the Marriott Union Square in the 7 days we stayed here. From knocking on our door when the Do Not Disturb was clearly on the door and we were sleeping off jetlag from a flight from Beijing, to having staff who could not offer simple directions in the city, to not knowing what an adaptor is for European electrical devices, it seems as if staff are hired to do a job that they are not trained to do. Truly, they all seem completely at a loss for the simplest request. I finally complained after 5 days of problems, and while the manager was sincere and really heard my concerns, I just think the problem goes deeper than the abilities of this night manager. They need a major service overhaul!!! I recommend that you try one of the other many great hotels in the Union Square area.