Held a business function here last year and never saw any member of the function staff the whole time. Service staff were quite disorganised and the function room allocated wasn't even up to par (ie, sound system poor, lighting wasn't great, etc).
It seemed that the hotel was only relying on it's great location and harbour bridge view to get customers through the door which is very unfortunate.

The Sebel Pier One is in one of the best spots in the whole of Sydney, right on the harbour next to the iconic bridge. Although the rooms are minimalist they are very well done and very comfortable. It is only a 5 minute walk to the rocks but for a quiet drink the hotel's own bar was very reasonable and it was nice to sit by the water.

I stayed at the Sebel Pier One for 2 nights over a weekend. The staff were friendly. The location is great - directly under the Harbour Bridge, very well located if you want to see the major sights on foot. Also a great place to stay to be near the Rocks. It is a short walk to Circular Quay/the Rocks (5mins) and about 10mins to the Opera House. I also walked to the Pitt St Mall daily and that was an easy stroll, though probably 20-25mins.
The hotel was fine. I saw the reviews about the toilets on here, and I'm not a very fussy traveller, preferring to find a great deal. For me, the bathroom looked stunning, but there was a lot of noise. The toilets flushing didn't bother me nearly as much as the pipes groaning while in the shower. It is a cute old building so that's fine, but it didn't make me think of five star luxury.
The rooms were spotlessly clean. They were small but well laid out. They didn't have a lot of natural light and you couldn't open a window which is a shame. Again - old building. It is nice to stay somewhere with a bit of character rather than a 70s style brick hotel with classic hotel colour scheme - but I probably couldn't stay for more than 2 nights in a place like this. Beds and pillows and room service and amenities all excellent. I slept well though the twin beds were pretty small.
This is fine for a quick trip to Sydney. If you are only there a matter of days and want to see a lot and stay in a hotel, reasonably priced , I think it is great. I probably won't stay there again as I have been to Sydney a number of times, and there are so many options I try and stay somewhere near whatever area I want to see. But if you are looking for a place in this location and the price is right, I think you will be happy here.

Stayed there for a week on business. The room was nice and clean. The service was fabulous and the location was perfect. The breakfast buffet was very good. It is pricey but everything in Sydney is a bit pricey - this was worth it.