I picked one up with that trade in your DS Lite deal at EB and also picked up GTA: Chinatown Wars (pretty awesome game for a hand held).
So as you probably know it's pretty similar to the old one except it got rid of the GBA slot (who cares). It has a slightly bigger screen and some of the buttons have been switched around to be more functional and also an improved set of built in speakers. Of course the main new difference is the introduction of the camera and it looks as though a number of DSi specific games will be released that react to your movements on screen via the camera which is pretty amazing again for a hand held system.
Unlike the DS Lite it has alot better internet capabilities with a free opera based browser. It's not the greatest browser but it's fine for a quick surf of the news or forum while you're on the dunny or something. It has also implemented a Wii-style menu rather than just having the option to run a game or settings/chat screen. From this you have the ability to download mini games from the Nintendo site using points just like Xbox live for example. Obviously the site is fairly void of content at the moment since it's only been out a couple of days but I can see it being a cool way to grab new applications and games in the future.
It also have updatable firmware unlike the previous model so we'll hopefully see some cool updates in the future. I guess lastly the DSi has a SD card slot so you can store photos and music and stuff on your DS. I haven't really played around with the music thing yet but it has a built in program to alter music and whatnot. On top of this is an image editor for your photos where you can do a bunch of weird crap to your pictures.
Overall it's a nice little system. If you don't have a DS yet then I recommend looking into it sometime. This post ended up a lot bigger than I intended but there you go, that's my ultra short review so far.
Also I forgot to mention that hitting the power button once gets you out of any program you were in and takes you to the main menu and holding the power button for a second or two shuts it down. The games can now also be hot swapped. Win.
It also have updatable firmware unlike the previous model so we'll hopefully see some cool updates in the future.Or theyll just use it to fight "homebrew"
I heard the DSi stops cards like the M3 and R4 from working? Confirm/deny?
Meh i have dslite and see no reason to 'upgrade'. Especially if i have to hand over $$ for games.