I like the idea of adding more expressiveness, pictorially capturing sometimes fleeting moments of emotion or accurately representing an emotional state that can occur. These are the following reactions: 1. +1 2. -1 3. smile 4. thinking_face 5. heart 6. tada Do they capture the necessary expressiveness for the context? Facebook's reactions cover more emotions, but FB is trying to support reaction to anything that can…
Considering that it's Github, how about things relevant to software engineering, like: agree, disagree, support, insightful, obsolete, misleading. I can't imagine it being helpful to know that someone felt "heart" about an issue comment.