It is not only that it is Perl-style; this version also supports multiline regular expressions.

I do not like that it requires you to know a file's line endings to use them, though:

    Mac.   : a\rb
    Windows: a\r\nb
    Unix.  : a\nb

I was able to do this in the previous version.

But is such a change worth a major version number increase?

Google Chrome Team started this kind of "bigger version" war, now Firefox/IE/Linux, they are all in it :-)

Nothing new. I remember Slackware 3.6 (?) jumping to version 8 in order to be closer to the other Distro's numbers. thought it was sorta stupid at the time.