The DSi LL is the best iteration of the DS hardware you can get. It has two big, bright screens, with a clear and crisp LCD display that has no ghosting. The colors are vivid, not washed out, with no gamma issues.
Even the controls are improved with very clicky and responsive buttons and D-pad. If you've only owned an original DS, this is the upgrade you've been waiting for. Possibly the only missing thing is a lack of GBA support but all the other positives make up for it.
This particular Japanese DSi LL (Super Mario 25th Anniversary) comes with Flipnote installed, making it easy to prepare for running homebrew programs.
Huge upgrade for those that fell in love with the original DS or DS Lite.
The DSi XL contains a lot of fun and the larger screens make this a must have for those who love the original DS lite. A great investment in a nice upgrade.