Q: What versions of the stock ROM does this work with?
A: It's known to work with anything from LF2 up to LHE. It seems likely that DebugFSRoot will be able to work with any ICS ROMs. We'll have to wait and see if it works on JB or not.
Q: I'm getting an error like "adb is not recognized as an internal or external command", or "cannot stat 'su': No such file or directory". What do I do?
A: Don't run the tool straight from your compression program. Make sure to extract all the files somewhere first.
Q: Will this wipe my data?
Q: How can I unroot? Will flashing a stock ROM unroot?
A: Flashing a stock ROM will unroot and also remove any modifications you made to /system.
Q: Everything seems to have worked fine, and the Superuser app shows the binary as present and working. However, none of my root apps work. What do I do?
A: This seems to happen to a very small number of people, and the cause is unknown. If this happens to you, try installing Chainfire SuperSU
Q: Is this any better than flashing the root66 ROM?
A: The end result should be pretty much the same, but this tool is much smaller to download than the root66 ROM.
A: If you are on a phone with the stock LG1 ROM update, root66 will downgrade you to LF2, while this tool will leave your ROM alone.
Q: Is this any better than using the VRALEC boot chain method?
A: The boot chain is a little more complicated. It requires flashing two bootloaders, flashing recovery, and using Triangle Away to reset the Custom Binary Download counter. If you intend to install a custom recovery/custom ROMs anyway, it's fine and probably quicker. However, if all you want is root to run Titanium Backup or other root apps, GS3DebugFSRoot is easier.
Q: Will this increment the flash counter?
A: Not on its own. If you flash anything else after rooting, however, you might, so read up on what you're doing.
Q: Will this cause the "custom unlock" boot screen to appear?
A: In general, no. However, the spyware Samsung/Verizon included (SysScope/libcordon) is paranoid, and a lot of tweaks you can do after rooting will trigger it. If you don't want to risk getting the custom unlock screen, don't freeze any apps using Titanium Backup and generally limit your tweaking to things you could do without root.
Q: Can Samsung/Verizon block this method in the future?
Yes. It's very possible that a future OTA will patch the exploit that this tool uses. If you want to root, it's always best to do it now!