how did you feel about the ending of the story?

It was really sad but very Steinbeck at the same time. Steinbeck was a master at the beauty and the pain of a relationship. The ending George gently goes through his familiar speech about what guys like he and Lennie got is poignant, sad and beautiful. George's mercy killing of Lennie is an act of love more than anything else. Lennie always trusted George to do the right thing for both of them. Unfortunately this was the last loving act George could do for Lennie, any alternative would have been much worse.