My SO and I have stayed in a wide range of hotels in China, in a wide range of places. Our suite at the Marine Garden was above average, but not quite "very good". Carpets were very stained and like other hotels we've stayed in, even very high end ones, the carpets are not vacuumed daily.
As other reviewers have noted, there are no elevators in this hotel and lots and lots of stairs, so it wouldn't be great for the elderly or disabled. There is an indoor pool, but it is not heated, as advertised. There is a guy who stands around in a gym suite occasionally and pops in and out of the area, who may presumably be acting as a life guard. You have to wear a swimming cap in order to use the pool.
We just came from the Sofitel in Hangzhou, where the concierge was just about the most helpful concierge I've ever encountered, so perhaps I judge this hotel's concierge desk unfairly. But the concierge and service in general strike me as indifferent (with the exception of one bell hop who picked us up from the port and gave us a tour of the island... very nice, talkative guy).
We stayed in the standard suite. Beds are hard, but softer than most Chinese hotels. I personally like the firmness. Pillows are fine, bathroom is clean, though the shampoo and soap provided in dispensers is pretty low grade. We've also had a hard time finding wall outlets to fit even Chinese appliances.
Be aware that mosquitoes are thick on this island. Bring insect repellent. Mosquitoes still manage to sneak into the room and I woke up this a.m. with about 20 bites on my face and arms, despite never having opened the door or window... eek.
Finally, food on this island is pretty terrible, compared to comparably priced restaurants in Shanghai and Hangzhou. Some of the small seafood restaurants are dishonest and overcharge you for seafood sold by weight, by overstating the weight of the item. Make sure you watch the item being weighed in front of you before you consent to the price! Also, there is not really much street food, which we really enjoy. The tang yuan (soup 'balls') we've had were not made with fresh seafood. Seafood 'pancakes', freshly fried in small alleys and sold to passing tour groups (which the island is thick with), were better. On the other hand, fresh fruit is plentiful and sometimes good.