We stayed over Christmas and New Year 2012/13 and will comment under different headings.
Location.
Good with excellent pools and beach. We used the adult only pool most of the time but the main pool looked great fun for the kids with waterslides and the lazy river for inflatables etc.
The ten minute walk to Karon along the beach was ok in daylight but at night a 200 baht taxi ride was a must as the main road is unlit and dangerous. The same applies to Patong which is too far to walk (about 4k) and entails a 400 baht taxi ride. Over a two week stay this adds up and is worth factoring in your calculations.
Room
We stayed in 447 which has a jacuzzi on the L shaped balcony together with a very comfortable seating area. The super large bed was very comfortable and feather pillows, our preference, were available on request. The Venetian blinds fitted all round were a bit of a pain as they are very low geared and took an age to raise and lower. This is a particular nuisance if one of you wakes early and fancies sitting out on the balcony as they are also noisy to operate thus waking your partner.
The room was quite large with plenty of storage, likewise the bathroom complete with a glass rain shower cubicle and separate toilet. The sliding wooden doors that separate the bathroom from the bedroom were jammed open and despite asking for it to be fixed nothing happened.As the toilet door is glass this meant reduced privacy when using the toilet.
We were supplied four bottles of water daily as tap water cannot be used for drinking. This was adequate for our daily needs and a small jug of fresh milk was delivered within minutes of requesting it for tea and coffee.
We only used the jacuzzi once as the brown water was a bit offputting. A constant temperature was difficult to achieve in the shower, hot and cold fluctuations being the norm.
Restaurants
My partner is a coeliac sufferer so gluten free is a must in her diet. On our first day Sandro Agulero the executive chef (Spanish) assured us that this would be no problem and went out of his way to ensure that her choices from the buffet and a la carte met her requirements. Not all of the staff were as professional and plainly did not understand her requirements,which was a slight worry but thankfully no harm was done. Perhaps a better understanding of this allergy could be incorporated into staff training.
The Cove Restaurant is where breakfast is taken and the choices were very good from the buffet, everything from bacon and eggs to cold meats and cheeses, cereals, yoghurts,fruit, all being offered in abundance together with tea and coffee and fruit juices although the latter could do with real fresh orange juice as opposed to the " made from concentrate" on offer.
In the evenings the buffet was again first class, the seafood nights being particularly good with everything you could ask for including rock lobster and fresh oysters. On other nights the hot meats from the carvery were also very good and again in abundance.The buffet charge of 990 baht although not cheap compared to outside prices is good value for what you get.The cheapest bottle of wine on the list is 1200 baht but is of good quality.
The Italian Restaurant, where we ate three times during our stay gave us the only reason for complaint. The first time it was faultless, food good and service equally so. The second time, a disaster. We waited half an hour for our bottle of wine to arrive, a further half an hour for our meals and when they did arrive were so poorly cooked and presented that a transport cafe could have done better. The excuse given was that several people had ordered at the same time! I complained and offered to pay for the wine but not the food.To be fair they apologised and accepted that it was not to standard and removed the bill for food.I spoke to Sandro the executive chef the following day and he informed me that he had been away the night before but would make enquiries. He was as good as his word and came back to me to apologise and also sent the chef from the Italian restaurant to do likewise (he was European). They both assured me that the next visit would faultless. We decided to visit again on our last night accompanied by a Swedish couple we had met. Sandro himself would do the cooking for us.
The food was excellent, the only problem was that we the men had ours served together, one, which was not that which had been ordered, of the womens a while later, and the fourth one not at all! As it was going cold we ate the first two served, the wrong meal was taken away and finally the two correct meals for the women, freshly cooked, arrived later. Profuse apologies from Sandro for the inefficiencies of the staff followed yet again but for a supposedly five star hotel this is not good enough.

Overall impressions.
We had a good holiday but this is not a five star hotel, it cannot compare with The Penninsula in Bangkok which is a real five star. Also, we preferred the Dusit Laguna where we stayed on a previous visit to Phuket. There, the New Years Eve Gala Dinner included complimentary wine throughout the evening and complimentary champagne at midnight. In the Centara Grand we had the impression that you pay for everything handsomely. The 400% tax on alcohol charged by the Thai goverment does not help but a little goodwill by the hotel would not go amiss on special occasions.
The dress code asked for in the hotel restaurants is ignored by most of the guests (many are Russians) and out of control children a pain in the neck. However, these are paying guests and it is difficult to know how to enforce it without causing offence.
We would not go back there but if you have children and are happy to stay in the hotel complex for the duration of your stay it would be a good choice as there is enough to keep them occupied safely day after day.