GM Goodwrench tools are hit and miss when it comes to quality. They are made by Stanley and most of their new tools are nothing more then re-labeled wal-mart tools with a much higher price tag.
With that said, They are some good ones also. For example, their ratcheting wrenches are Blackhawk/proto clones. They even share the same GA warranty address. Unfortunately, they also share the same price tag if purchased new. Especially the singles. ($19.99 for a 7/16" non reversible wrench). But they can be had used quite cheap.
They also made composite adjustable wrenches that are clones of the Blue-point, Greenlee, pro-set etc brands. They even have the same PAT number on the handle.
IMO their warranty *****. I purchased my ratcheting wrench sets from O'rilleys and the 18mm had a deep scratch on it right out of the package. O'rilleys would not exchange it without the receipt (X-mas gift), and it took 6+ weeks for me to get it back from proto/blackhawk. And even then the new wrench came back as a "GM performance parts" wrench, not a "GM Goodwrench" (Same wrench with different name).