I agree with Gemini, the two best purchases we have made are an AP and Full-Enclosure.
Most Raymarine AP’s can operate as either a “standalone” (hold course based on the fluxgate compass heading) or in Chart-Plotter “route-mode”.
If you have a chart-plotter engaged (and have it connected NMEA/Sea-Talk) in route mode to follow waypoints, then your AP can be programmed to follow this route and alert you when you have arrived at a waypoint, then request your approval to change course to next waypoint. (also adjusts for set and drift)
Also, the Raymarine AP has an auto-tack function for sailboats. You press the +1 and +10 button together and the boat will tack 90 degrees (or whatever set it for). Great for single handing.
As Gemini says, you can adjust the pilot rate of correction. We have ours set to a moderate mode, with the main reason so the wheel is not correcting all the time and using batter power.
Using an AP has improved my personal piloting immensely as I had (have) a tendency to over correct the wheel to often and too much, which leaves an “S” wake, and from a performance standpoint every time you turn the rudder it slows the boat down. I now engage the AP, leave my hands lightly on the wheel, and let the AP teach me when not to correct 🙂