Brent,
Your finish work looks very nice. Walnut has a very rich, pleasing look to it.
I do see an issue with it, not one that you did buy from the way the wood was cut. If you look at the end grain you will see that there is grain running in a half circle (the wood came from a very small branch or the center of a tree). This causes warpage and splitting of the wood over time and drying. You third board down in the glue-up actually has the very center circulat grain of the branch, the most prone to cracking, twisting and rotating of any part of a tree. When selecting wood, always avoid this, or cut the wood so that it does not happen. The grain idealy shoud only run diagional to your piece. Your two upper boards would have had more strength if it was cut lengthwise and half of the board flipped, then glued back togeather. The third board down should have been trimmed and the core of the tree disposed of and wood used more to the outside. I hope this makes since.
Aaron