The MiJam Guitar is a guitar simulator which you can plug into your iPod to jam along to songs. It looks like a playstation Guitar Hero controller. There are four preset styles: heavy metal, rock, blues and bass. The fret board on the neck features four sensors, which allows you to the basic chords and riffs.
It has tempo, pitch and volume controls so you will always be in tune with your backing track. The "strum bar " is used for picking notes, riffs and chords. It plays a bit like a guitar and is portable enough be used with your iPod or music device anywhere you go.
But if you want a portable guitar-like instrument why not buy a ukulele? Or you could get a ukulele kit for cheaper than the MiJam.