This is a pretty straight forward hall pedal. The spring reverb sounds great, I like it just as much or more than the one in my amp. Until 12'o clock I'd say is the normal range of reverb for me, higher settings are good for an extreme effect. One thing important to know is that with higher settings, all parameters of the hall change, so not just decay and mix, but also predelay. The features on this pedal are a bit limited in that sense, in return you get the very small size.
One thing that is a small problem for me is the loud acoustic click-noise when you turn the pedal on and off. The switch has more resistance than the one on my freeze and is also a lot louder, this is a problem for me because I play a lot of quite music, and initially I wanted two have a little amount of hall set on my amp, and use the holy grail to add more hall. At the moment I try just switching between more and less hall by turning the knob with my foot, which works pretty well, or I will get a new, quieter switch for it someday.
With a quieter switch, this would be the ideal hall pedal for me, because it sounds very good and is so straight forward, you can't loose yourself on the knobs because there is just one ;)