I also ha e the Samsung Galaxy S3 the iPhone is just better. Very smooth and snappy yen pictures are awesome. The galaxy is more like a toy time than a serious piece of technology. I like the galaxy bit just not for everyday all day use. Even the 4s was better than the galaxy. I just don't use widgets and find myself doing everything in my iPhone. I always say of is a personal decision. Go to the store play with them both and enjoy whichever you choose. Good luck.
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