Most people probably don't know this, but when Nintendo brought the awesome Brain Age to North America, they added one feature before releasing it - sudoku. It added a bit of value to an already stellar cartridge, and managed to take advantage of the current puzzle craze in North America.
It also made Sudoku Gridmaster - a very vanilla version of digital sudoku - almost obsolete.
On the one hand, you have Brain Age, which features sudoku along with a dozen or so other activities to keep you entertained for $20. On the other hand, you've got Sudoku Gridmaster, which features nothing but sudoku (with four times the puzzles) for the same price.
Increase in puzzles aside, Gridmaster is arguably the lesser game when it comes to the puzzle aspect. The interface in Gridmaster feels so clunky next to Brain Age. It takes way too many commands to set placeholder numbers, and they're so tiny that they're hard to see. Plus, if you choose to use the number drawing feature - instead of putting in numbers by tapping an on-screen keyboard - you'll find the stylus recognition to be pretty dodgy.
Technically Gridmaster delivers exactly what it promises: sudoku on the DS. There's nothing particularly wrong with this package; it just feels so bare-bones compared to even the more mediocre portable versions to come before it. Where's the multiplayer mode? What about an option to create your own puzzles? Heck, even a few more music and background options would do something to make this feel a bit more worthwhile.
Considering the handful of sudoku games already available for the DS and Game Boy Advance, it's hard to recommend Gridmaster at all. Heck, even Go! Sudoku on the PSP delivers a better experience than this despite the lack of a touch screen on the system.
If you've already completed every sudoku puzzle in Brain Age and you just can't get enough, Gridmaster is definitely easy on the wallet. But it should be your second (or even third) choice for a portable sudoku fix.