
It's been several days now since I started playing
Pokemon SoulSilver, which was just released in North America, and more than enough time to post my impressions on the unique device that's bundled with the game--the
Pokewalker.
The Pokewalker is basically a pedometer or step counter with an LCD display, and is the spiritual successor of the
Pocket Pikachu, a similar pedometer that was released in 1999. Unlike the Pocket Pikachu, the Pokewalker isn't a virtual pet simulator at all; it's more of a Pokemon digital transporter, where you upload any of your Pokemon from HeartGold or SoulSilver and take it with you anywhere.
The Pokemon inside the Pokewalker can "stroll" through different courses that are downloaded into the Pokewalker, and gain Watts for a certain amount of steps. Watts are spent to battle other random Pokemon found in the courses, giving you the chance to capture that Pokemon.
Your Pokemon can also find random items, and once you return your Pokemon back to the game, every item and Pokemon you've captured will be downloaded into the game along with it, and your Pokemon gains a level as well.

Both the Pokewalker and Pocket Pikachu use infrared signals to exchange data, and both can also exchange data with duplicate devices. However, a Pokewalker used with a copy of HeartGold or SoulSilver will become exclusive to that copy, and can't be used in other copies of the games.
I have several Pocket Pikachus, and while the Pokewalker wins with its excellent Pokeball design, the Pocket Pikachu wins the display category hands down, since its LCD display is in color, while the Pokewalker's display is monochrome. The Pokewalker also uses a quiet sensor chip that detects motion, unlike the typical pedometer mechanical system used by the Pocket Pikachu that rattles every time you shake it.
For what it's worth, the Pokewalker is an excellent device that enhances the Pokemon HeartGold and SoulSilver experience; having it included in the games at no cost is an awesome bonus for Pokemon gamers, who get the additional benefit of becoming healthier by subconsciously promoting walking in order to use it, LOL.