The emojis being inserted in the new version are bigger and more attractive and therefore superior.
However, they appear to be inserted in a weird way which causes the editor, at least on Linux (Thunderbird 52.1.1) to behave very oddly.
1. Insert an emoji at the beginning of the message body.
2. Note that your text cursor disappears. Usually when this happens when you insert an image, you can make it come back by unfocusing the window and focusing again, but that doesn't work here. So, the disappearing cursor is a problem.
3. Try to move your cursor before the emoji you just typed so that you can add text before it. It's impossible.
4. Backspace to erase the emoji, then type ctrl-z to bring it back. You can't -- undo doesn't work.
I'm sure that all this is at least as much the fault of the editor as it is of the add-on, but it's still all a problem.