This collection of stories introduces some good new characters and adds some backstory for others and their teachers, but really it's Earthsea itself that gets fleshed out, and particularly the magic school at Roke. The stories cover a range from the foundation of that school through a sort of coming-of-age tale about Ged's teacher Ogion, on to the immediate aftermath of the previous book, Tehanu.

I didn't find the end of the last story satisfying, but Le Guin described it elsewhere as a bridge to the final book, so perhaps it's just intentionally so. I'll certainly be coming back to Earthsea sooner or later--I seem to read about one of these books a year--so I will find out.