From Unofficial Sony Ericsson Blog, the new Walkman phone borrows a group from the design of new G705. The similar square shape, the same display and front-facing camera positioning.

Rika has devoted music keys instead of the traditional navigation pad included in the G705. Also, the Walkman handset has a brushed metal finishing, which makes it look pretty distinct
Rika should bring Wi-Fi, GSM and HSDPA connectivity and a camera of at least 3 Megapixels.