I had never had a goatee before, but tried a few months ago and upon shaping it for the first time, it was evident that I was going to have a problem with making it symmetrical, even, balanced, etc. I researched trimming methods and came across the GoateeSaver. This is really a great tool and you can get a very sharp and great goatee out of it. The product works great and it produces a goatee I would never be able to do on my own. It is quick and easy and the results are just great, I highly recommend it.
There are two points worth mentioning, however, not related to its ability to produce a quality goatee. The mouthpiece does not work very well with me. It does not conform to my face very well when using and it doesn't position itself well. I have found it much better to simply press it against my face. To get clean lines, you will need suction. You need to press it tightly against the skin and shave around it. This will ensure that the razor blade will be equally flush with the template on all sides and result in an even goatee. It does not seem to be possible to get a good hold on the face if you are just using the mouthpiece and I can't foresee how this would result in an even goatee.
I used the smallest setting and did not extend the size, however, if you choose to do this, it might be hard when you touch-up to find the exact setting again. There are no digits or markers when making the size adjustment to tell with precision how far you have turned the wheels and extended the sides. While you could simply leave it at the same size after each use, the wheels might turn slightly between usages or during cleaning and you could lose your former setting. To counteract this, I simply leave it on the unextended setting, but I envision it could be a problem if you extend it and would have to self-correct the dials by hand to the size of your goatee each time you want to touch-up.
I am extremely happy and I in no way had any experience with goatees, but it looks absolutely great.