The kind of problems you've mentioned are typical of thoughtless "what a cool mod!" changes to a design; these often ignore practical issues such as the volume change you've mentioned. However, 'fixing' these issues would require a bit more work and a few more parts, attributes that seem commonly not to be important in low-end pedals.
But, yeah, good for starting players (although even then I'd recommend a cheap multi-fx unit); beginners often don't even know what certain effects are, and once you know enough to feel you need a 'proper' version of effect you're better off getting something this is a step or two up from the cheapest available.
(disclosure - part owner of Prophecysound Systems)
Yeah, I suppose if you wanted to do the extra bass mod right so that your volume level is mostly the same when going "hot", you'd also need to tweak the series resistor value as well to get the gain of the snubber to match up. Guessing you'd probably also want to drop down that parallel 470k as well.
But, yeah, good for starting players (although even then I'd recommend a cheap multi-fx unit); beginners often don't even know what certain effects are, and once you know enough to feel you need a 'proper' version of effect you're better off getting something this is a step or two up from the cheapest available.
(disclosure - part owner of Prophecysound Systems)