The idea behind this game is a good one, so much so that it has been copied time and time again on most platforms. However, How Old Is Your Brain has some major flaws, that ultimately prevent it from ever being totally accurate.
First things first, a review of the game itself. In a nutshell, the game provides tasks that are supposed to improve your memory, general brain functions etc, such as quick maths problems, colour recognition tasks and other such challenges. All of these in principle are fantastic ideas, if not a tad boring. Infact these tasks do get you working up a mental sweat after just minutes of play. The better you get at these tasks, the more you unlock, meaning that you have something to work for, at least for a few weeks, other than reducing your brain age. The tasks in this game, although dull in comparison to the brilliant Big Brain Academy, are good.
The problem with the game, is the way the tasks are undertaken. All rely totally on either voice recognition, or the user manually writing answers of the touch screen. A nice idea in principle, however the DS has problems with the recognition. For example, the colour tasks requires you to say the colours you see on screen. On nearly every attempt I have had at this puzzle, i've had at least one occasion where what i say is completely misinterpreted, causing a wrong answer, causing time lost, causing higher brain age etc, you get the picture. Then onto the touch screen. The idea of a lot of the tasks are that you have to complete them as quickly as possible. This means quick writing. This also equals unrecognised digits. The DS will often pick up 5's as 8's (for me anyway) and loves to randomly pick a number for you on the odd occasion...Once again, this all leads to inaccuracies.
In fairness, it's a nice idea, but it's also been done far better by others since. The only real plus for this title is the 100 sudoku puzzles included with the game. That's all i use it for now. For actual brain training, I suggest Big Brain Academy.