What are the artistic features of Huai Su's calligraphy?

Huai Su, the date of birth and death is not allowed. Yi Shuo was born in the 13th year of Kaiyuan (725) and died in the 9th year of Yuanhe (785). The word hides the truth, the common surname is money, and then he became a monk. Yongzhou Lingling (now Changsha, Hunan) people. After moving to Beijing. Good drinkers are called drunken monks, and together with Zhang Xu, they are called "drunkards". Compared with Zhang Xu, Huai Su has a thick book and a thin book. People describe his cursive script as "walking on a snake" and "a whirlwind of showers".