Counting this new release, there are now nine Sudoku games available on DSiWare in Europe. Some offer a little more than others, but all in all it tends to come down to the price and amount of puzzles available. Crazy Sudoku does well in both areas, but with so many other choices which all have better presentation it's a tough sell.
Instead of offering a set of pre-made puzzles to slowly try and beat, Crazy Sudoku opts to let you randomise puzzles with your own settings. This includes six difficulty levels and two grid sizes (9x9 and 6x6), as well as the ability to turn hints on or off.
While playing, you get a number of points to spend on hints. You can either spend a small number to put the correct number in one single square of your choice, or you can spend a larger number to erase all incorrect numbers you've entered. If you enter an incorrect number anywhere, you are not notified, sort of similar to free mode in any Picross game, meaning that this hint is the only way of knowing you made an error until you've filled in the entire grid and the game doesn't end.
Aside from playing randomly generated puzzles, the only thing you can do is play more of them together with a friend who also has the game. This is done by taking turns of one minute each to fill in numbers on the grid. Each correct numbers gets you one point, while an incorrect one will cause you to lose 10 seconds of your remaining time. It's pretty fun, but of course, you'll have to find someone else who has the game as well, which could prove difficult. There is also a highscore list in which the game keeps track of various insignificant statistics, such as the amount of times you've played every grid size.
In terms of presentation Crazy Sudoku is as basic as it can get. The graphics are incredibly minimalistic and the music is, inexplicably, almost non-existent: they bothered to create music for the main menu but none plays during actual gameplay.
With no real sense of achievement in clearing randomly generated puzzles rather than a limited list, it's hard to recommend Crazy Sudoku over more rewarding experiences like Sudoku Sensei. It is only 200 DSi Points, however, so if you are in incredibly dire need of randomly generated Sudoku puzzles with little else, it might be worth a brief look.