I found HF cordless tools to be OK, but like many have mentioned before, the weak point is the NiCad battery. One of the best out there are Milwaukee cordless and they have a nice selections in either 12V or 18V. Mine are all 18V Li-Ion, and they work flawlessly. We have a tool wholesaler nearby who runs his business out of a barn in the country, and he gives some outstanding deals on Milwaukee and DeWalt tools, so I got them at a good price.
For those of you who are concerned about torque values when tightening with an impact wrench, look into the torque bars, commonly called torque sticks. Not sure I would use them to torque a cylinder head, but for getting the proper torque on a lug nut, they work great. Here's a link to HF's set of torque bars:
Harbor Freight torque bars