The Slacker app uses the Wi-Fi capability to refresh stations, which you can choose by connecting the player to your computer. Once a station is refreshed, the content is cached on the device and you no longer need a wireless connection to listen. You can "heart" and "ban" tracks directly on the device itself.
The main issue with browsing is the lack of a full QUERTY keyboard. It makes inputting Web addresses and search terms fairly tedious. This is something that could be addressed with future firmware, we suppose.
Sony also took steps to integrate the Wi-Fi into your own music listening experience. A "related links" feature on the playback page will take you to either YouTube videos or a Yahoo search of the artist/song playing.
One of the coolest interface features on the X-Series is the tilt-and-scroll feature for video scanning and album art browsing. Press your finger to the screen, swipe to one side, and see snippets fly by, tilting toward the direction of your pull.
One of the coolest things about this player is that you don't have to use the touch screen to control playback. Sony included tactile play/pause and track shuttle buttons on the top edge of the Walkman.