«  "Simple, accurate, functional and cheap. Only the microphone could be better" »

I use it for over two years. The battery still works nickel. The advantage is that you can use it three ways, effects loop of the amplifier with its input and output jacks, one input (unplug the guitar to the amp), or the built-in microphone (but less accurate, plus it captures some harmonics). System with flat / sharp can be placed any note, however, we would have preferred a chromatic tuner! This is the only one I tried, but it works. € 22 is pretty cool. I would do this choice, unless there is a cheaper model.
PS: it is solid, the fact that to fart in the face dropping the amp, and I never had any problems.
-1 For the microphone is not so precise.
-1 Because it is not color, although it can be used as adding sharps and flats (up to 7), but it's been doing calculations!