(Jan 2010) Got this bag for my kids 2 DSi's. It will fit both, along with 20 games, but it is not very roomy. If you have a silicone cover on the DSi, it does not slip in & out of the bag very easily as the bag is felt lined and the compartment for the DSi is fairly snug. You definitely couldn't fit a DS in here with the Nerf Armor case on it. While I complain it is not very roomy, it is not meant to tote around 2 DSi's and the accessories that go along with both of them. If you wanted to use this for just 1 DS & accessories, it would be perfect because everything that goes along with it isn't very large anyways.
It has an adjustable strap that can fit a child nicely, yet adjust to fit mom & dad too. The strap attaches with a spinning hook, which I find great because it doesn't get all twisted. You can even remove the strap and use the handle on top of the bag if you wanted to. Lots of room for extra stylus (slides into an elastic strap to hold in place). Overall, a great little bag that doesn't take up too much room and keeps the DSi's safe when not being played...I wouldn't worry about the DS too much if they were inside and the bag was dropped.
******UPDATE******
(Feb 2010) I actually can fit my sons DSi in the bag when it has the Nerf Armor foam case on it. It is very snug, but it does fit!! I have 2 kids, which means 2 DSi's...so I'm ordering another Nerf case and I think this bag will hold both of them with the cases on. I'll update then and also add a picture showing them both in there.
****** 2nd UPDATE ******
(Aug 2010) Well, we have had this bag for almost 8 months and it is still the perfect bag for my kids 2 DSi's. I never got around to ordering another Nerf Armor case as I stated above, but I don't doubt it would fit both of them if needed to. With the DSi's in it, this bag has been dropped, had drinks spilled on it, been in the middle of tug-o-war matches, and still looks fairly new. I only wish it could hold more games as time goes on and their game collection grows.
****** 3rd UPDATE ******
(Dec 2010) About a year later, our DS family has grown to now include a DSi XL. This bag WILL fit the XL, could even fit 2 XL's snugly beside eachother. The newest additon, the XL, is mine (yes, parents have toys too!)...I still keep my kids in the pockets and just stick mine in the front of the pockets. It floats around loosely, but everything is felt lined so it is perfectly safe. So the ultimate DS bag has just become the super ultimate bag that can transport 2 DSi's AND a DSi XL safely!! Yay!
****** 4th UPDATE ******
(Dec 2011) Almost two years later, and this little bag is still the best option for our families "gaming" needs. We have 3 kids, and between them, there are 2 DSi's, a DSi XL, 2 iPod Touches, and as of a few weeks ago, my Kindle Fire...all of which WILL fit in this bag! They don't all have their own little compartments, but they fit and stay fairly organized, and easy to access...but most importantly...safe!! It still looks brand new despite a few of the threads unravelling from the embroidered "2 squares" logo on the front flap...and that is barely noticable. Every once in awhile, when it's smell becomes unbearable from all the spills and other "unknown" icky stains, I toss this bag (haha, empty, of course) into our front loading washer and wash it. Comes out brand new and smelling awesome!