Taco Hoekwater
* Additional hyphenations (in typewriter text). These were added because luatex is willing to hyphenate words that start with a non-letter: luatex just starts the word at the first thing that is a letter. An argument can be made for maintaining compatibility, but currenty we do not intent to make that change as the new behaviour is desired much more often. (the same can be said for hyphenating the first word in a paragraph, but that case never arises in the texbook)
Do you have an example where the new behavior would be desired?
* Extra or slightly different ligatures. These are caused by stuff like the self{}ful example above, and this incompatibity will definately remain. TeX's exact behaviour was an implementation artifact that is pretty hard to mimic, and any attempt to do so would lead to extremely ugly code.
Ugly code and ugly/inconsistent results. -- David Kastrup