Got a chance to test the X briefly. Initial impressions are the build quality is solid. The granite edging provides a reassuring grip and kudos goes out to the materials selection/design engineers. Like the large Home and Hold buttons. The smaller top Play/Pause, FF, RW buttons have a nice tactile feel to them. The shiny plastic back of the X is a fingerprint magnet. With the A829's matte metallic casing, the decision to go with a glossy back on the X is a step backwards. They should be using the granite material on the back for a consistent feel in the hand.
The OLED screen looks good though images lose their pop under fluorescent lighting. The screen is a tad small and the low QVGA resolution makes video watching seem like an afterthought than a distinct selling point for this PMP. Sure, there are battery life savings, but the OLED screen is unfortunately not used to its full potential for video. Menus are fairly intuitive and the scrolling is fluid. At times, pressing the icons/controls does not respond and requires a more deliberate push. Listening with my E500s, the sound signature is similar to the warm A829 with more refinement in the bass department. I'm somewhat torn as I wanted the X to be a home run; however, my initial experience is mixed and the price premium is hard to justify with questionable implementations--browser, Bluetooth, file support, etc. If you're interested in audio ONLY, prefer the Sony sound signature, and don't have a decent pair of sound-isolating IEMs, then the X may fit the (extra Benjamin) bill. Otherwise, the S9 offers a more favorable video experience for a $100+ less or wait for the verdict on the Zune HD. Hopefully, it's a balanced PMP with excellent video AND audio to compensate for the lack of control buttons and (most likely) FLAC support.