How is Bian's calligraphy?

Well, there has to be a standard. I suggest you look at Wang Xizhi's Preface to Lanting (known as the best running script in the world) and Preface to Saint Education.

Yan Zhenqing's Sacrifice to the Nephew (the second running script in the world) and Su Shi's Huangzhou Cold Food Poetry (the third running script in the world).

Look at Wang Xizhi's Yuan Guan Tie, Duck Head Pill Tie, Zhi Yong's True Grass Thousand Characters and Sun's.

Look at Huai Su's bitter bamboo shoots and Huang Tingjian's all-seated posts from the book spectrum.

Only with exemplary standards can we know whether it is good or bad.

The first two pictures are ok, but the last two are not flattering. Of course, good and bad, different people have different views, each has its own advantages, and sometimes it will be very different. You can decide according to your own preferences.