What can be done better? Improved sharpness and better detail overall. Recovered detail in very light areas. (these get lost even if the overall exposure is good) Decreased shadow noise with increased detail. Can even correct for lens distortions and chromatic aberration. You can create default settings for each lens/camera/ISO combination, so it isn't necessary to manually make all adjustments for each shot.
It really isn't difficult, but you do have to take a bit of time to learn how to use the software. The commercial products JimC mentions are available as trial versions, and there is Raw Therapee as well, which is highly capable.