The manufacturers description is this,
The DS finally gets its very own Web browser, as Nintendo firmly embraces the Internet age and finds some clever new uses for the touch screen and stylus.
The lowdown:
The DS Browser comes on both its own DS cartridge and a memory pack that fits into the GBA slot of your DS (there are two version of the Browser, with memory packs to fit either the original DS or the DS Lite). The obvious benefit of surfing the Web on a DS is the large screen area afforded by two screens and the stylus – which also makes typing in Web addresses a lot easier. The problems though are a low screen resolution and the fact that the browser doesn’t support Flash files, movie files, sound files, PDFs or anything else that needs a plug-in to work. As long as you recognise the limitations though, this is still a cheap and easy way to access the Internet when on the move.
Most exciting moment:
The big problem with accessing the Web outside of PC monitor is that it doesn’t all fit on screen at once. The DS overcomes this problem in perhaps the most elegant manner yet, with an option to put an overview of the whole page on the top screen while letting you scroll around on a zoomed in version on the touch screen.
Since you ask:
The DS Browser is based on a PC application called Opera, developed by Opera Software. The same company is also creating a version of the browser for use with the Wii console, which will be free for the first six months of the console’s life.
The bottom line:
Surf the Web on the move, but don’t expect an entirely smooth ride. -HARRISON DENT
Manufacturer's Description
Opera Software will deliver the World Wide Web to Nintendo DS users via the Nintendo Wi-Fi Connection. In Opera's agreement with Nintendo, Nintendo DS users will now be able to surf the full Internet from their systems using the Opera browser. The Opera browser for Nintendo DS will be sold as a separate DS card. Users simply insert the card into the Wi- Fi enabled Nintendo DS, connect to a network, and begin browsing on two screens
The Opera browser for Nintendo DS is based on the same core as the Opera desktop browser, delivering superior speed and rendering of web pages on the Nintendo DS. Using the DS card, users can connect the internet with the WiFi-enabled Nintendo DS via a HotSpot or wireless router, and begin browsing absolutely free.
With an on-screen keypad and stylus, users can easily navigate the Web from their Nintendo DS with PDA-like functionality. The two screens are used for multifunction purposes -- both can show one web page together, or one can show a zoomed-in view of the page, and when typing, the bottom screen shows the text being entered while the top shows the webpage you are on.
--------------------------------------------------------------------------------
But an actual review from someone who owns it is this,
If I didn't have any real use for this browser and just bought it on a whim, I would probably be writing about how below average this is, and like many other people, touting that it's no way a replacement for it's PC counter-part.
However, the DS browser is something that's come in useful for me. Whilst away in France; it was my main way of communicating with those back home. I was able to email friends and family and keep in touch with people that I needed to. It was also a good way for us to find activities and services local to our destination.
Also, this is good entertainment whilst wasting time in train stations. I can often find myself sitting around, waiting for a train, and having the opportunity to check my emails and surf my favourite websites.
Technically, the browser has it's flaws. For starters, and most notably, it's very slow; though this can be somewhat forgiven, since it renders pages really well, and can display them how they look on your large PC screen. Also, the browser fails to support plug-ins such as flash, and other media types - but this is down to the console itself, and not the software.
I like this bit of kit. It does what it needs to, and though it has some flaws, can come in really useful. Think hard about whether you'd actually use it though. It's not a toy, it's a tool.
Hope this helped