I don't even know where to start in answering your question, but let me say that I can't imagine owning a boat without an autopilot!

Initially I was very, very skeptical/hesitant to buy an AP....after all, they're a very big investment and I could argue that they really aren't essential. So when I finally made the decision to spend the money, I was kinda nervous that perhaps I was buying yet another toy that I would never use....BOY WAS I WRONG!!! I use my AP all the time. Here are some of it's key selling points:
1. Unlike my friends, it can hold a course perfectly, it never gets tired and it doesn't complain.
2. It saves me fuel. I can plot the most direct course and it sticks to it with amazing accuracy and precision.
3. Even though most of the time I'm still at the helm (i.e., ready and waiting to disengage the AP and manually pilot if I encounter an obstacle), I find it does 98% of the work and I arrive at the fishing grounds much more relaxed and ready to fish than if I'm manually piloting all the way.
4. It's in dispensable for solo fishing. For example, sometimes when I'm fishing for salmon, I'll engage the AP with one key stroke to go into a large, slow circular pattern when I hook a fish. I also use the myriad of pre-programmed patterns such as zig-zag, concentric circles, s-curves, etc. when fishing tuna as I find that often tuna hit when you change direction (i.e., rather than going in a straight line). Yeah, I can do this manually, but doing that for hours on end is painfully monotonous...this way, the AP does the work while I eat a sandwich and wait for the reels to start screaming.
5. I've programed routes for the best approach and departure from my harbor. Sometimes when the fog is super thick and visibility goes to nearly zero, I turn on the radar and my AP and drop my speed to a slow putt-putt....that way I can focus on looking for boats that may be on a collision path with me in a more relaxed manner (i.e., I only have to worry about one thing). N.B., it only takes one quick push of a button to disengage the AP and then I can take the helm in a nanosecond to make whatever safety maneuver necessary.
I could go on and on, but my advice is simple: JUST DO IT! Do get a quality unit: Simrad, Furuno, etc.. If you're reasonable mechanically and electrically inclined, you can install it yourself, but if you're at all unsure, pay a professional...money well spent.