I love this restaurant, it just opened recently I have been there at least 10 times over the past couple of weeks. They serve relatively authentic Hunan food, which is not easy to find in HK - yes that means it's quite spicy.
One of the dishes to judge the quality of a Hunan restaurant is the fish head and theirs is spot on - I usually go for the half green/half red variety, which is juicy, flavorful and spicy. Don't forget to order some noodles to soak up the soup. Lamp cutlets with cumin are also highly recommended: good meat with a strong cumin rub, nicely grilled. From the veggies I would recommend the fried cabbage, great texture and lots of chilly (a but oily). They also serve the typical Hunan rice in small clay pots.
However two negative points: their Hong shao rou (红烧肉) is quite weak - flavor is to mild and texture is also not right. Secondly the service is a bit patchy: they sometimes forget dishes, it can take ages to get rice etc.
The place is not easy to find: it's a narrow staircase up from the street. Interior is quite basic and they only have around 10 tables, which fill up very quickly, so be early or book in advance.