Probably the biggest advantage of a cordless tool, regardless of type, is its portability. They can go anywhere you go, whether it be the shop, your garage or your yard, without having to find a place to plug it in or being limited to where you can go by the length of the cord. Most of the cordless tools purchased today come with a two battery power pack. When one is low on power just simply replace it with the fully charged one. They are also very compact and can be stored out of the way easily. When you buy them they come in kits so you can normally get a drill, a circular saw, possibly a pin nailer and a flash light, so you really have multiple tools in one.
Lets compare some different tool uses where one might be better than the other. On power drills, if you are drilling a lot of holes in cement that has been aged, the corded hammer drill would be your best choice. Even though there are cordless hammer drills on the market, you would need the continuous power of a corded drill to get the job done in a reasonable length of time.
If you are using a circular saw, it would depend on what you are cutting as to the choice you should make. If you are cross cutting or ripping a 2 x 6 or 2 x 8 and doing a lot of them, then the power of a corded saw would be helpful. On any other type of cutting, either one would do the job well. The same thing would hold true with the reciprocating saw. It would depend on how big of a job you are doing.
Some disadvantages of the cordless tool are the loss of power if you are using it for a long length of time. The cordless tools are heavier and the additional 5 to 8 pounds of weight can put a strain on the body after using it for hours.
A disadvantage of the corded tool is the cord itself. It seems like it is always in the way. You can trip over them or cut them with a saw. These are both safety hazards. Also as mentioned earlier, you are limited to as far as your cord will reach. You have to find a longer extension cord or find another place to plug it in.
The info in this article is strictly the opinion of the writer. It is not meant to infer which tool is best for you. Hopefully this will give you some insight on things you have to consider when buying a corded or cordless tool. I am a home owner and a do it yourself type of person. I have a workshop and have used tools of different types for a long time. To solve the problem for me as to which one I should buy, I have both the corded and cordless tool. Now I just grab which ever one is best suited for the job at hand. If I could only buy or own just one it would be the cordless tool. For the average home owner that would be sufficient for most jobs he would encounter. Again, this is just my opinion.