This is a version of sed based on GNU sed. It is not a version of
GNU sed, though.

There are several new features (including in-place editing of files,
extended regular expression syntax and a few new commands) and some
bug fixes; see the NEWS file for a brief summary and the ChangeLog
for more detailed descriptions of changes.

The biggest note, i think is the *huge* speed difference, where
regular sed might take a few mins, super-sed can take only seconds
this is not true in all cases, and sometimes you have modify your
regexp syntax, however for the speed increase, it might be worth
it.