I had the possibility to stay at Mandarin Hotel during a week in October of 2011. The hotel offered our group very good basic business rooms, relatively good service and all things necessary.
The hotel is situated a few blocks from the Guangzhou East Railway Station, so getting to the hotel is rather easy and fast if you are coming from Hong Kong by train. You still need to get a taxi though, it's not a walking distance.
The hotel has gone through a name change in the past history, since our reservation through travel agency was under a different name (Dongfang Hao Chen Hotel). But the address was the same and pictures on the website matched the Mandarin Hotel. This caused some confusion with the taxi driver though since I had the name written in Chinese as well.
The level of English skills was minimal in the hotel (which should not be a surprise to any China traveler), so be prepared to spend some extra time with check-in and out as well as when ordering food and doing pretty much everything. I did not mind the extra hassle, but please keep an open mind and lots of patience.
The Guangzhou exhibition facilities as well as the recreational river banks are 20-30 minutes form the hotel, but with taxi prices, this does not ruin your travel budged (3-4 euros per trip), but it's more of a hassle with the timelines if you have tight schedules.
My room was spacious, clean and everything worked. The only minor issues could be the fact that right next to the hotel is a military or police academy with their execise field. The groups start their training with marching songs rather early in the morning and this keeps on going through the day. If you need to work in your room, you will be entertained by their songs through the day.
One interesting discovery was the huge Karaoke service in the hotel. The concept of "Night club" which is advertised on the hotel wall means three floors or Karaoke rooms. Each floor has around 50 rooms which is rather impressive. No women hotel guests were allowed.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC