At 5.3 by 2.8 by 0.9 inches and 10.2 ounces, the Wolverine ESP is not supersleek and is far from sexy. It has much more of a utilitarian vibe than most media players due to its unassuming gray plastic exterior, 4:3 screen, and mundane user interface. Still, the unit's definitely pocketable and extremely durable, and importantly, it's intuitive. Plus it holds up to 120GB of data.
To the right of the 3.6-inch 4:3 TFT display (320x240 pixels) is a nice five-way joystick. Above the joystick is a mediocre mono speaker, and under the joystick fall the tactile Menu, Escape, and Volume buttons. These controllers coupled with the simple GUI make the ESP one of the more straightforward devices I've used in a while. The only other buttons to pay attention to are the power and hold slider located on the right spine. The left side of the ESP is rounded and padded with a softer plastic (though still a little slippery); the ESP is designed for righties.
You will notice two flip-open panels on top of the device: one is a CompactFlash Type I/II slot, the other an SD/MMC/MS slot. Stick a memory card in, and the ESP will ask to back up photos or the entire card. Transfer times are decent-- I backed up my CompactFlash card with 76 JPEGs and AVIs (about 55MB) in well under a minute. These files are placed into a new folder in the main menu's Backup option, and they are easy to access and view (either in list mode or thumbnail mode, with two rows of four thumbnails). Incidentally, the ESP's USB 2.0 transfer rates are speedy (55MB in about 10 seconds).
Of course, there are some MP3 players (such as the Toshiba Gigabeat S and the Cowon X5) that can move photos over directly from a digital camera, while others such as the Creative Zen Vision:W have a CompactFlash slot. Furthermore, there are PVPs including the Archos 04 series that make excellent photo viewers. But none of the mentioned can play back RAW files like the ESP. The ESP also displays full EXIF data, and photos look bright and sharp onscreen (though we've seen better resolution). You can easily zoom in and rotate.