A preview pane isn't exactly the same thing. OSX also has this in column view. But Quicklook will popup a modal window, which can be resized as big as you want, so you can get a clear view of the file content as good as actually opening it in its app, without the added overhead of actually having to launch [and quit] that app.
[and, if the file in question is a Photoshop or Illustrator document, you'll really appreciate how much time QuickLook saves you, by not having to wait for those behemoths to creak slowly into action]
There are also certain plugins which can enhance this functionality by providing extra info, such as pixel dimensions on image files, allowing browsing inside archives, syntax highlighting of source code files etc.
Maybe peoples' descriptions on here aren't doing Quicklook justice, for those who aren't familiar with it. Once you've used it for a while, you can't imagine why it's not a standard feature on any modern desktop OS.
[and, if the file in question is a Photoshop or Illustrator document, you'll really appreciate how much time QuickLook saves you, by not having to wait for those behemoths to creak slowly into action]
There are also certain plugins which can enhance this functionality by providing extra info, such as pixel dimensions on image files, allowing browsing inside archives, syntax highlighting of source code files etc.
Maybe peoples' descriptions on here aren't doing Quicklook justice, for those who aren't familiar with it. Once you've used it for a while, you can't imagine why it's not a standard feature on any modern desktop OS.