This is going to be a short review. Not because the free and open-source S.M.A.R.T. Monitoring Tools aren't useful, but simply because they're, well, simple. Run from the command line, they tell you everything you need to know about your hard drive's health, i.e., the S.M.A.R.T. (Self-Monitoring, Analysis, and Reporting Technology) info and you can even instruct them to initiate your drive's S.M.A.R.T. self-test.
Commands are in the format smartctl -(command) -(drive). E.g., smartctl -h sda. Notice that the command uses the Unix/Linux protocol for drives (sda, sdb, sdc, etc.) instead of drive letters. That's a hint at the tool's heritage.
My only, and exceedingly minor, complaint about the S.M.A.R.T. Monitoring Tools is that the information it presents is often wider than the 80 characters that the Windows command line window defaults to. To alleviate this problem, increase the width of the command window by left-click on the "C:\" icon at the top left of the window, select Properties, select the Layout tab and increase the width of the Window size to 120 or 160.
The S.M.A.R.T. Monitoring Tools are great, and for instances in which you can access only a command prompt, invaluable. That said, most users will be better off with Passmark's DiskCheckup (free), which will relay the same information via a graphical interface.