The phone is a bit sluggish to respond to key presses and the screen is slow to refresh its contents. I noticed these issues particularly when scrolling through menus or lists such as when looking through track listings in the music player and when viewing folders containing thumbnails such as camera images. There's a little wait for the screen to populate with thumbnails, and the more you have, the longer it takes.
I'm going to skip right to the camera at this point. It's a very mixed bag and both pleases and disappoints. On the downsides are its on paper 1.3-megapixel rating, lack of a flash, and terribly squeezed on-screen viewfinder. That small screen lends about three quarters of itself to the viewfinder with info bands top and bottom taking up the remainder.
Now, a Walkman branded phone is not expected to carry a top-notch shooter, but given the specs, images were pretty good. My standard indoors test image, the coloured dish, is really quite sharp, and its colour reproduction spot on. Outside, the chair suffers a little from a lack of colour uniformity but the image is strong considering the camera spec. The flowers are a little over exposed - their yellow is a tad darker than the photo suggests, but I'll take it.
If you want to store images, or indeed music or anything else, you'll need to resort to Memory Stick Micro cards as there is only 5MB on board the phone. The slot is behind a rather fiddly right side mounted cover. Even then, Sony says only cards to 2GB are supported, and indeed the phone was unhappy with my 8GB card, which it insisted was not formatted.