The moment I saw Roadie2 at a trade show - I wanted to own one.
Now that it's in my hands I really think its good.
I set it up to tune my 5 string guitar to open G.
Its a breeze to use and all you do is press it onto the tuning peg and pluck the string a few times. it usually gets it in 1 or two plucks and is very quick.
It then gives a beep sound and the lit end circle shaped LED changes from blue to green.
The only problem I have had was when I plucked the wrong string (Doh!) its doesnt like that and after trying to tune - it gives you a red light warning (which is fair enough)
I tried it on 6 guitars and it worked great - the only instrument it failed on was a nylon strung child's ukulele but that is really just a toy. It worked on other nylon strung acoustics.
Its micro USB charged and holds a surprising amount of charge for something doing forceful mechanical rotations.
I love gadgets and am super pleased with this one.
Check it out!