How small is the Sidekick? It measures 4.7 x 2.3 x 0.7 inches and weighs 4.5 ounces. Compare that to the Sidekick LX, the only other model T-Mobile currently sells, which measures 5.2 x 2.4 x 0.7 inches and weighs 5.8 ounces.

The designers have managed to slim the phone without compromising on existing features. The Sidekick is a quad-band worldphone (850/900/1800/1900 MHz) with the same 64MB of onboard memory. The phone also comes with a 512MB microSD card.

Battery life is just slightly less this time around, but not by much. The Sidekick is rated for four hours of standby time, like the LX, but only 5 hours of talk time, as compared to 6 hours with the LX.

Besides the slimmer shape, the newest Sidekick stands apart by the shell customization it offers. Users can easily remove two panels—a larger one covering the back and one end, and a smaller one the covers the opposite end-and replace them with colored shells of their own choosing. Each package comes with a set of metallic green shells.

Owners should visit sidekickshells.skinit.com, where they can choose from a wide variety of looks (for $14.99) or design their own custom shell.

The Sidekick's button layout and interface were so well designed from the start, that there have only been slight tweaks since then. This Sidekick offers no surprises in that department. The front is dominated by a 2.6-inch, 400 x 240 pixel screen, which swivels up with a nudge from a thumb (we liked the movement of the Sidekick Slide, but the swivel screen is back).

We were happy with the Sidekick's performance in our testing. It offered reliably strong call quality in the New York area, and the 2 megapixel camera produced images with a good range of colors.

This Sidekick is a much-needed addition to the line, but we'd love to see more advanced features next time around.