We just got our invisible fence this month and we and Bailey LOVE it.
There is some training involved, but the manual has a step-by-step instructions on how to train your dog to it.
She liked to wander off to the neighbors to 'do business' or visit if they were in their yard or garage. She would not stop and come back when called. So, we had to go fetch her (and clean up her mess) and apologize. Fortunately, both neighbors are friendly.
So, we had to keep her on a leash in the yard

, or go drag her back home.
Now, she can RUN and PLAY 'free' and still be contained in the yard. We're always in the yard with her so we're not worried about other animals/critters getting into our yard.
This was the best purchase we've made for Bailey.
Read up on them though. The one we got is WIRELESS and works on radio signals. It only works in a circle (but the size of the circle is adjustable), so make sure that will work with your property layout.
The shock is adjustable and one of the lowest settings works fine for Bailey. The collar beeps when she gets close to the boundary before it gives a shock. The shock is just to get their attention, it is not to electrocute them. (and Yes, I tried it on myself). BTW, if they DO run through the boundary, the shock stops after 30 seconds. They, can then cross back into the boundary without a shock and it is automatically reset.
And, actually, sometimes Bailey goes outside without the collar on, but she now automatically stops at the invisible boundary.
The step-by-step training plan was for 14 days, but Bailey learned much quicker.
We and Bailey BOTH love the FREEDOM that it gives her now!!
YMMV