It's similar, but there are some differences (which may or may not be important):

1. the local $/ has a very tight scope which may be important if you read additional files and don't want to get them in slurp mode.
2. no global filehandles.
3. a minimum of error handling
4. filenames hardcoded only once

well, you can also get point 1 with an ordinary block, e.g.

my ($content, $IN);
unless (open ($IN, "<", $file)) {
  die "Error in reading '$file': $!\n";
} # unless
else {
  local $/ = undef; # valid only until end of block
  binmode($IN);
  $content = <$IN>;
  close ($IN);
} # else
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Global filehandles have a problem: they are global, and if you open(IN, ...) and another IN is already opened, the first IN is closed. In some cases (e.g. recursions, reading filenames out of a file and opening them in a subroutine) this may be fatal.

point 4 is in my eyes important that it is not good to write something like:

unless (open ($IN, "<", "file1.txt")) {
  die "Error in reading 'file1.txt': $!\n";
} # unless
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I agree with everything, and follow those practices myself. I just stopped reading after I read what I thought was the point of your post. ++'ed.