The initial coverage will use millimeter wave (very high frequency) spectrum, which isn't great for range and may serve as more of a stopgap. The kind of coverage you're used to will have to wait until later, when AT&T can justify moving 5G to more commonly used bands. That shouldn't be too hard when much of the LTE equipment it's installing now should help with the migration, but that still entails a wait.

This will still make AT&T the first big carrier to launch 5G. Sprint's rollout is expected in 2019, T-Mobile only anticipates national coverage by 2020, and Verizon has so far talked more about its fixed 5G than something you can carry in your pocket. However, AT&T can't quite claim a resounding victory. It's making some sacrifices to shout "first," and mature 5G won't arrive for a long while.