This is good advice. A not-too-heavy, high-quality cordless drill is excellent for driving screws, turning bolts, etc., as well as drilling small holes. If you ever have to get into tight spaces or work in attics, crawl spaces, or outdoors far from an outlet, it's great. And often, especially in tight quarters, you don't even want all the torque a good-quality plug-in drill develops -- it can smash your hand if it catches on something.

And having a plug-in, high-power drill (preferably with a hammer feature if you might be going thru block, stucco, or concrete) is an excellent complement.