While still a fan of digital stand-alone metronomes, I feel that the ubiquitousness of smartphones and iOS devices makes these devices an incredibly useful place for a useful metronome app to live, both in my own studio and those of my students.
The problem with many metronome apps (both for Android and iOS phones) is they happen to be so feature-rich that they can get difficult to navigate around the most basic functions like finding a specific tempo marking, finding a subdivision (if you need one) and turning the sound on.
This is the main reason Metronome Plus is quickly becoming the go-to metronome app in my studio. I haven't got time to dither around trying to customize the controls of some sleek ad-infested app with a complex interface. I need an app that is ready to go without any lag time whatsoever.
On opening Metronome Plus, you're presented with a small wheel at the bottom of the screen flanked by a plus and minus sign that toggle the tempo speed. The play button at the upper right turns it on. If you need further customization, you can pull down a menu from arrow at the top ofthe screen, which has settings for meter, subdivision, accent location, and sound types (I still like the default digital sound, although clave, woodblock, and shaker sounds are also available).
And that's about it. The attractive yet minimal architecture of Metronome Plus doesn't promise so much at first viewing, but over time it's the kind of metronome app that I've been coming back to over and over again.
And did I mention that the digital pendulum animation that moves from side to side looks kind of....Cylon?
Finally, I should also mention that although this app was designed for the iPhone/iPod Touch series of devices, it scales extremely well on the iPad (where I use it daily), with barely any pixellation on the larger screen.