I'm not sure the new code block editor is a step forward. Here are the list of issues I have with it:
You can't edit the text in the block once you've closed the block. If I can't edit it directly then I should have an option to edit the block inside the block editor again. Right now you have to select the text and copy it, paste it into the block editor and then make your changes. Then go back to the original block and delete it.
Selecting the text from the block doesn't always seem to pick up all the text. It seems to skip the first few lines on occasion. Might be me but I've had it happen twice already.
It doesn't remember the default language. It would be nice if it remembered my default language because the default of Markup is really annoying.