I had high expectations for this game, but was slightly disappointed when I bought it.
I think it's definitely a good buy for any brain trainer though, and would recommend it all the same. It has a Daily Play option, which makes it easier to quickly challenge family and friends without having to create a profile, as well as the option to create 4 profiles on one card. There is the Brain Age Test, which has 3 random tests, as well as Training, with a range of different tests, which are unlockable depending on the number of stamps that you have. All of the tests are good and do challenge your brain, and it's good to have a graph result at the end so that you can easily see your progress...or in some cases, not! There is also a few hints after gameplay, about some hidden features of the game as well as how you can improve your brain whilst out and about.
However, for me, the reason why it's not 5 stars is because, although you can take the test as many times as you want in a day (though your result is only recorded once daily), you can only train in each test once per day. Also, I think the speaking function of the game is quite limited, making it difficult to successfully complete the Stroop Test and Speed Counting.
Overall, I'd say it was worth buying the game, but don't go in with too high expectations as you may be a bit disappointed!