The basic results of the test are this: if you're looking for speed and you live in or around an urban area, AT&T is the best option; but if you're in a rural area, Verizon is the better choice.
The interesting part of the testing is that in most of the areas tested, T-Mobile's HSPA+ network posted faster average download speeds than even Sprint's LTE network. The great equalizer though was T-Mobile's "average time to first byte", which was about 3x slower than any other network. That means, once your download gets going, T-Mobile offers great speeds, but it will likely take a while to get that download going. T-Mobile's LTE network largely gets rid of that delay, but is too small to really make much of a showing in the tests.
If you want to drill down into your specific region of the country to see how each carrier fared, just head to the source.