The NW-S23 measures 3.1 by 2.0 by 0.8 inches and weighs only about 2 ounces, but it actually feels a little smaller, thanks to its odd-yet-nifty contoured shape. Designed to be held in a closed fist with one's thumb placed squarely on the play/stop/select button (which is surrounded by grip-friendly rubber), the NW-S23 makes for an ideal exercise companion. And it comes with an equally stylish and functional armband that the player screws into. The player's rubbery, gray neck includes the forward- and reverse-track buttons that also serve as menu and Group navigation buttons. These buttons are designed to be pushed with the same thumb, which makes for an occasional and mildly uncomfortable contortion, especially when you're adjusting the menu settings. The dedicated volume buttons are nice, but they're easier to operate with two hands. That said, the player still maintains an ergonomic, durable feel overall with a perfectly placed headphone jack, inherent water-resistance, and a big, fat play button.
The front of the player includes the Group button for navigating through various folders of albums or artists (Sony's own version of a playlist) and a Sound/Repeat button. The latter button toggles through the player's three treble/bass settings (Normal, User 1, and User 2) or the numerous repeat functions (All, Single, Group, Shuffle Group, and Shuffle All Groups) depending on how long it's pressed. The two-line, backlit LCD is noticeably small, and while necessary information such as battery life and scrolling track titles is displayed, it's just not that impressive. The minuscule screen also makes it difficult to surf through menu options, which show up one item at a time. On the back of the player, you'll find a Hold switch, a menu button, and a button that opens the water-resistant, rubber-sealed battery cap. The USB port lies next to the sealed battery compartment.
While the NW-S23 does play MP3 files natively (in other words, MP3s are more than just "supported"), the player doesn't have any notable extra features. There's no FM tuner, no voice recorder, no stopwatch, nada. It's important to point out that there are excellent 256MB players out there, such as the JetAudio iAudio U2, with many more features at prices lower than the NW-S23's $180. On a positive note, the dearth of features keeps the player simple, which is a good thing since the small display makes for a weak menu experience. The menu options include Display, which allows you to choose from basic track info, detailed track info such as format or bit rate, or elapsed time; Volume, which you can set to manual or to a static volume level; Sound, which selects the treble and bass settings; and Repeat Mode, which includes Normal, A-B loop, or Sentence repeat, which is ideal for spoken word audio. You can also turn on or off the AVLS volume limiter; the blue backlight; and the annoying beep, which, by default, sounds with every push of a button.
Those already familiar with the Network Walkman family will know that you must use the included SonicStage software to transfer ATRAC3 and ATRAC3plus files. Prior to the NW-S23, those with MP3 and WMA files needed to use SonicStage to convert them to Sony's proprietary format. With the NW-S23, you still can't simply drag and drop music files onto the device, which shows up as a drive letter without software on Windows XP. You must first open an application called MP3 File Manager that resides on the device itself. This enables you to drag and drop your MP3s (or the folders containing them) into the utility's window, and voilà: your player is ready to play back MP3s. The player also supports Sony's Connect music store, which features more than 700,000 tracks downloadable in ATRAC3. Sony includes five free Connect downloads with the player.