Circular saws are useful for cutting lumber, plywood, posts or even metal. You can make beveled cuts as on a compound miter saw, and with the addition of guide rails, it's possible to make long straight cuts that would otherwise require a table saw. (ConsumerSearch has separate reports on miter saws and table saws.)
We found the best circular saw reviews at Tools of the Trade Online, Popular Mechanics and Fine Homebuilding - all based on excellent comparison tests. Popular Mechanics covers several budget models priced for occasional homeowner use, but oddly enough, doesn't pay much attention to safety issues. This is surprising, since the Consumer Product Safety Commission finds that most power tool accidents involving blades occur to homeowners and hobbyists. Most budget circular saws lack blade brakes, but expert reviews recommend these as an important safety feature.
Woodworking and construction publications, including Fine Homebuilding, the Journal of Light Construction and Tools of the Trade Online do cover safety issues thoroughly. Tools of the Trade also provides excellent comparison tests of eight lithium-ion-powered cordless circular saws. These batteries offer quite a few advantages over the NiCd and NiMH batteries that power most cordless power tools. For example, lithium-ion batteries maintain their charge better during storage, meaning you'll be less likely to find a drained battery in your cordless saw.
We're noticing some improvements in budget circular saws, since nearly all now come with carbide-tipped blades. However, the tests at Popular Mechanics show that the least expensive circular saws make it much harder to make accurate cuts or to follow a long cutting line, even with a guide rail. So, for hobby woodworking or do-it-yourself construction projects, it will be less frustrating to invest a bit more in a better circular saw. Reviews recommend consumer-brand circular saws - models priced below about $130 - only for occasional rough cuts where precision doesn't matter, and where the user is paying extra attention to safety. The most recent review at Tools of the Trade Online, for example, finds that it's too easy to accidentally start both the Firestorm FS1500CSL (*est. $70) and the Worx WT431K (*Est. $120).