Ifixit has given the recently released DSi a technical first look and on their site they discussed what the differences are between the DSi and the DS Lite.
For example, the DSi uses a smaller rechargeable battery (840mAh) than the DS Lite (1000mAh), supporting previously heard statements that the DSi would have less battery life than its predecessor. The DSi’s additions, such as the long known SD/SDHC expansion slot, are also discussed.
The article on the DSi’s first look can be found here.
IGN has also reviewed the system. They were not positive about the cameras’ capacities (though stating that comparing it to an ordinary camera is unfair) but were very positive about DSiWare. Their full review can be found here.