Prospecting direction isn't borked entirely. Enders has a fix for it, but I still have trouble figuring it out, and occasionally using the same Q extract the node just disappears on me even though i'm in the same spot. Standing directly on the node will give proper readings, but there's a bit of luck in that. And it doesn't work well for cave systems when the vein is in the walls somewhere and you don't know which way to mine.
I'm using Enders. I've prospected and followed the arrow, only to reach dead ends. I've doubled back to re-prospect, only to be told there's no ore detected. I've moved around, back and forth, 10 tiles, 5 tiles, 1 tile, and been told all sorts of interesting things. And yeah... it seems like, if you follow the positives, you might eventually find something. So I did.
Finally had it tell me "there is a tin vein below" or somesuch. Moved one tile off, prospected again. Nothing found. Move back to the tile it told me there was ore. Nothing found. Move a couple tiles away. Get a directional arrow pointing back at where the supposed ore vein was. Move back there, nothing found. Move a couple tiles away, move back, prospect again, tin ore. So I figured there was probably something there.
I snake-tunneled through rock to get to where it, hypothetically, was. Over 50 tiles away with a Q29 stone axe... took far too long, but I figured the reward would be worth it.
Finally reached the spot a little while ago. Nothing but Q10 rock. Continued on, in case my counting was off. Still nothing for another 5 tiles beyond the point where ore should have been.
I say it again: Prospecting -- even with Enders -- is borked.