Only for the hardcore Sudokuers.
I do have some qualms with the overall experience though. You don't feel like you're accomplishing anything by completing puzzles. They could have at least had some unlockable wallpapers or new music tracks in there to make you want to complete all bajillion puzzles. Also, there are loading times *gasp*. I was amazed because it's freakin' Sudoku!. It's a 9x9 grid of empty spaces or numbers, what in the world is there to load for like 5 seconds each puzzle? The game also has the annoying habit of loading (who knows what) in the middle of a puzzle. This lasts for 5 seconds or so, and is an extremely irritating flaw.
The puzzles themselves do look really clean and sharp. The mix of backgrounds is decent as well as the different sound effects for different puzzles. The music is kinda fitting, but it may start putting you to sleep after a while.
It has an online mode too, which is kinda cool, but you prolly won't find many people on there or think it's worth playing all that much yourself.
There are definitely better puzzle games on the PSP out there and better Sudoku games on the PC; however, if you're a diehard Sudoku fan looking for some handheld goodness, give this game a shot although it may be hard to swallow a price tag for something like this.