They serve different purposes. The Galaxy Tab's biggest strength is that it can be used on one hand rather easily and is much easier to manage outdoors. It really is a big smartphone in that sense and I don't mean it in a derogatory way. If you have a smartphone and love using it on the go but wished the screen was bigger, the Galaxy Tab is for you.
The iPad on the other hand is a more of a sofa lounge device. It doesn't have the same type of portability but instead is to be used in place of a Laptop or Notebook. It's much harder to use it on one hand and a bit too big for outdoor usage. However it compensates that by having apps that are much more customized to fit the larder screen real estate.
So while many like to pit these devices against each other, a quick trial of them will tell you they are similar but different enough that you have to know really what you want out of your tablet.
The iPad on the other hand is a more of a sofa lounge device. It doesn't have the same type of portability but instead is to be used in place of a Laptop or Notebook. It's much harder to use it on one hand and a bit too big for outdoor usage. However it compensates that by having apps that are much more customized to fit the larder screen real estate.
So while many like to pit these devices against each other, a quick trial of them will tell you they are similar but different enough that you have to know really what you want out of your tablet.