No matter what mode of public transportation you take or what time of day it is, you're almost guaranteed to see somebody tapping away at the strange, two-screened game system known as the Nintendo DS.

There's a reason the DS is the most popular video game system of all time: It has a simple, intuitive touch-screen interface; it's portable, has a long battery life and, most importantly, the games are a lot of fun.

The Nintendo DSi, the third generation of the immensely popular handheld video game system, hit store shelves in the U.S. on April 5. The first couple of days saw enormous numbers, with a reported 300,000 units being sold in America within the first 48 hours.

Since its launch in late 2005, the DS has undergone a couple cosmetic changes. It's the same system, just sleeker.

The majority of people buying the system aren't getting a DS for the first time, but are instead upgrading their current system for the latest version. But with the economy in such a bad state, why are so many people spending money on a slightly shinier version of a product they already own?

Marisa Zaragoza, a biology major at SF State and employee at GameStop, said appeal may lie in the DSi's new features. The built-in camera, web browser, and SD card slot give the game system additional features that make it "a lot like a smart phone."

"I love mine. I like it way better than the DS Lite," Zaragoza said. She keeps hers in a pocket at all times to show curious customers and friends.

The Stonestown Mall GameStop had over 50 people put money down early to reserve one of the coveted handhelds, and people call every day to ask if they're in stock. And while college-age gamers are the biggest chunk of the market, they're certainly not the majority.

The DS is extremely popular with girls, more so than any other video game system. It's no wonder that Nintendo uses celebrities like Beyoncé, Carrie Underwood and Liv Tyler to advertise its system.

One of the biggest draws of the system is the downloadable game service that allows gamers to get games off the Internet using the device's built in wi-fi. There were only a few titles that were eligible for download at the time of the launch. Until the catalog is expanded, some consumers, like Michael Webb, an SF State art major, don't see a need to buy another DS.

"The camera was cool, but I played my friend's for 10 minutes and got over it. I'm not spending that much money until they have some decent downloadable games," Webb said.

GameStop is offering special trade in deals for customers wanting to trade their old DS for the DSi, making the hit on the wallet a little softer. And while the allure of the system may be irresistible for a while, time will tell if people can be happy with their now officially "old" DS systems.

"I'll get a DSi eventually," Webb added. "I just have more important things to pay for right now, like rent."