Sound — 10
As far as tuning goes this thing is pretty much dead on accurate all the time, especially with bass and Acoustic guitars where the body is meant to vibrate a lot. And the fact that its chromatic makes changing to alternate tunings mid set, or tuning your guitar down a half step easy easy.
Overall Impression — 10
I'm buying this item as a stocking stuffer for every guitar player I know this year (and maybe another for myself since the bass player in my band keeps stealing mine). For the price this is perhaps one of the most useful pieces of equipment I have ever had.
Reliability & Durability — 10
I've been using this for almost three months and I haven't even needed to change the battery yet. I've dropped it several times and its fine. I keep it in a pocket of my equipment bag (which takes a good tumble in the back of the van every now and again) and it has yet to falter in its performance.
Ease of Use — 10
You just clip this little guy on your headstock and turn it on... it does the rest. The LED lights let you use it pretty much anywhere. I can't imagine tuning actually getting any easier. I run my guitar straight into my amp and turn the volume down when I want to tune.