I shall endeavor to keep this brief, since there is not much to say about this product. It is a fairly robust (and cute!) digital instrument tuner,and it costs $2. I think it's a very worthy little app for... fans of the digital tuner genre. Very cheap, functional, and practical.
I'll give you guys a little backstory. My (guitar) tuner inexplicably vanished into the ether a couple of years ago. I refused to buy a new one, since that would mean realizing the loss of the old one (and compounding the loss of the one before that). Ever since, I've been a tuning vagabond, tuning to songs on the radio, tuning to other out-of-tune instruments, even tuning to nothing at all! Enter the Nintendo DSi Tuner. My only concern was its quality. Well, I've only used it a couple of times, but it does the job. The Nintendo DSi Tuner has fast, accurate, responsive note recognition with the onboard DSi microphone, a choice of 3 interfaces (one of them with a confusing, but cool Game & Watch motif), the ability to tune to other pitches (like those of another instrument), and a Balloon Fight mini-game, complete with Balloon Fight music. I love Balloon Fight. The mini-game isn't exactly AAA, but it's a neat little time-waster, and it might make a decent drill for beginner musicians. The tuning screen also has a mini-keyboard (just one octave) that generates a tone to which you can tune. So the app is also something of a digital pitch pipe! I had a bit of fun playing around with the keyboard, though it was rather limited, tiny, and rough. It even gave me an idea for a potential iPad killer app: Virtual synth with piano lessons and limited sequencing. Please don't steal my idea.
Anyway, what was I talking about? Oh, yeah. The Nintendo DSi Tuner. It's good. If you think you might want it, then you should probably get it. The Metronome seems to have a better mini-game, but metronomes are boring and lame.
Tuning a guitar to this is lot easier than relying on my ears and a piano. ;)
The A can be adjusted to be anywhere between 435-435Hz, and you can switch between lettered notes, and do-re-mi (key of C).
I'd been wanting a pitch pipe and was pleasantly surprised when I got one as well as the tuner. Previously I had to bring the KORG game with me to have a small keyboard to poke notes out on, and this is a lot more convenient to start up (except for the single octave restriction).