Sometimes they will surprise you on depth. The deepest coin I dug with my 202 was a silver Rosey in red clay under damp sand. that coin was at least 9" down and that clay was hard as a rock. it took me a couple minutes to dig it out. I'll never forget it.
OTOH, I used it on a grassy field and did dig lots of targets. it was only after getting the Delta and going back over that same field that i realized how much I was missing. It was a HUGE number of targets; believe me, and many of those were deep coins; many of them sitting sideways. the 202 just didn't see them.
But overall, as I've always said, "muffler on a stick" BH machines are quite functional for what they are and what they're designed to do. The will find treasure.
Some of the higher end models are pretty darn good imo. I have an old Radio Shack Land Star clone that I got for 25 bucks that will hit fairly deep in AM mode. I don't use it anymore but one kid I take hunting from time to time really likes it.
The most important thing is enjoying the hunts regardless of what you're swinging...