The Powers-that-be on both sides decided that it was a terrible thing.
British officers were disciplined over it, German offices transferred, disciplined, even demoted.
Little reported is the fact that the Canadians quietly said "Scroo you!"........ and had their own Christmas truce in 1915.
Source of information? My grandfather, who was there with 54 B'n. He said it was a strange thing, "standing out there in the middle of No Man's Land, talking with a German. You gave him a tin of bully and he gave you a sausage, you traded buttons off your uniforms. He showed you pictures of his wife and kids and you showed him pictures of yours. You traded names and addresses and promised to meet, after the War..... and then you went back into your trenches and you tried to kill each other."
Pretty hard to forget. Impressive words, even at second-hand.