This was in my "stocking filler" wish list for a while, and at the price, it was a no-brainer to add it to my order. I was amazed at the quality of what I got, and at how useful this has become.
One thing that confused me at first was the measurement of a standard (mono) guitar cable; in positions 1 and 3, two yellow LEDs will light, but this is correct because the test is also for TRS ("stereo") cables. A mono cable appears like a TRS cable with the ring and sleeve short-circuited.
The only criticism I would have is that the LEDs are super-bright and can almost blind you in dimly lit environments (i.e. most gigs!), and other than that, the device is built like a tank (+) but tanks are heavy (-), and this might be a bit heavy for a small kit bag.
Summary: just buy it, you won't regret it.