Works great, but if you aren't extremely vigilant while using it, you could either lose a finger/fingers, or wind up with a log in the gut from kickback, or both. Not the safest tool in the shop, but it really does work well for smaller tenons. May need to make some modifications to it to allow for larger tenons sometime down the road.
Here's a step by step of how to use it:
Again, this is NOT to be considered a "safe" tool jig. Proper protective gear is essential as is proper setup and operation. Making tenons using this jig can be very hard on the tablesaw, as well. Slow as you go is the only way to move the piece into the saw blade. Keeping your hands back on the piece is also essential. As you can see from one of the photos above, it would be very easy to forget how close your hands are to the saw blade. If you do, you might just be minus a few digits in very short order. Best thing to do is make your pieces long enough to begin with so your hands don't even come close to the blade, and then lop off the extra length when your tenon is done.