Brisket can be done at different temps. When you can probe the thickest part of the flat with a skewer and feels like you are sliding into room temp butter. That is when it is done. It can be anywhere form about 190 to 215 depending on the piece of meat and cooking method. If it is tough, then it was underdone.
Bingo - Very well put! I remember that was one of the lessons I had to learn.
I've had a couple briskets that didn't give up the ghost until around 225°. You just never know.
I like using a long candy thermometer to test. Like Billy said, when you slide in a probe, once you get past the bark, it should feel like room temp butter (no resistance). If it pushes back at all, then the tissues need more time to finish breaking down.
After you do this a time or two you'll get the feel of it and it'll make sense.
The slices look great. Good smoke ring!