Yesterday I tried Layout Builder on my wiki, and, I got way more satisfaction than I got with createplates. But it's still not perfect. Here is a list of all cons I noticed:
Input boxes are too long
Wikia, make an option to change input fields size between two-lined and one-lined. I liked one-lined infobox input in createplates. But now, more than 3/4 of my layouts is infobox filling. We don't need entire line for two words and even one number.
Wikia, make Section widget along with Paragraph one. Paragraph is simple multi-lined input, and if it's optional and blank, and it's only thing in a section, then the section will be empty, and unneeded section header will appear on page. It's not good. For example, my wiki describes some maps in development, and tactics are unwriteable, so, leaving Tactics paragraph blank creates unneeded section containing only navigation box. Not good.
No ability to port page to a layout
If a pre-LB page complies new layout, why don't make a button to port it to layout without deleting it and all its history? I have 5 articles about maps and 4 articles about powerups, all complying layouts, and Layout Builder shows 0 pages in layouts, so, editors lose ability to edit page in layout mode.
IDs of widgets do not increase in code editing mode
Bug. Boring bug. Fixable bug.