Most of the Epic's specs are well known as well as how it will match up against other phones. At Engadget, they were able to receive one and do a test run on it. They went through a brief checklist including the Hardware, screen, software and its overall performance.
The 4" screen isn't the same as the Droid X and HTC EVO's 4.3" screen but not too much of a noticeable difference. The keyboard doesn't add that much weight to the phone and is very nice, it also comes with a front facing camera. The same Galaxy S Super AMOLED screen, it will come with Android 2.1 with 2.2 closely following. The epic also supports the same 1GHz Hummingbird CPU of the Galaxy S all in all this looks like a very solid phone.