Pros and Cons thus far for me. (Luckily the 'cons' are pretty (/very!) nit-picky. I just wanted to air my grievances)

Cons

• No smart not-match operator. !~~
• Perl 5.10 goodness not enabled by default. (I don't want more boilerplate.

  #!/usr/bin/perl
  use strict;
  use warnings;
  [download]

  is bad enough without use feature ":5.10";
• Perl 5.10 command-line goodness requires a chorded key (shift+e). I'm way more prone to typo'ing when a chord's involved. I know I'm going to type -lnWE and -lnwe<shift> a billion times. But, more likely, I'm going to patch my perl to make 'e' like 'E'.
• Boo for deprecating my $foo if 0;. Rightfully so... but still. :-)
• Boo for non-alphabetical release orderings. ("5.8.8" gt "5.10.0" -- I warned you these were nit-picky.).

Pros

• Hallelujah for finally adding // and //=!
• say "Hallelujah"; I'm already finding myself correcting print join("\t", @foo), $/; to the far Perlier say join "\t", @foo;

Hmm. The 'pros' list is shorter than I thought it'd be. Nonetheless, I'm happy overall.