how does this compare to thousand splendid suns? better?

I loved both of them :) I thought the kite runner had a happier ending in some ways, but A Thousand Splendid Suns had a more interesting structure, with the two stories coming together. Still, I couldn't say which one I liked more ... Khaled Hosseini is a brilliant writer.

Haven't read the latter; who knows, maybe it could be better. But I doubt it very much if another character will be able to last an impression on me as did Hassan.