Just to supply a counterpoint, The Rad City I've been riding the last couple of seasons now, the one with 1200 miles or so on it, have been adjusted one time since new and work just fine hauling my 300+lb butt down to safe limits on some pretty big hills. They work just fine, leaving me confident I can stop safely any time I want to.I own a Juiced CrossCurrent Air and initially my brakes came with Shimano M375 mechanical brakes.
I later upgraded to Tektro E715 hydraulic brakes. There's no way I can recommend mechanical brakes to anyone. I use my bike as a daily commute and I had to adjust it like once every 2 weeks.
The mechanical brakes work great only when they're brand new, or right after the adjustment.
If I were to get a Rad City (or any bike with mechanical brakes for that matter) I would upgrade the brakes as soon as possible.