It's a great phone. I had the 3G, then the 3GS version, now the 4. The retina display is a big improvement in terms of graphics quality. It's also thinner and really quite sturdy with or without a case cover. Haven't had any issues with the antenna, though, with a case cover (tried three different ones to find one I like style-wise, and would recommend a Speck case).
The apps are great for shopping as well. You can get apps for Gilt, RueLaLa and HauteLook on there and be one of the first to shop during the day.
Get it!!!