One of my favorite things about the these is they come in big sizes. The medium sizes especially are useful on sandstone route but are also great for granite walls. The medium and large sizes can often be more secure than a Black Diamond Knifeblade or Black Diamond Lost Arrow
They also give you a good range for clean aid if you want to try and hand place them. These have great durability. I have punished mine pretty hard on El Cap and they hold up relatively well.
One major dislike is the cable size. They come with #2 size cable which is strong enough when new. However, after you place and clean them about 20 times, the thin cable starts to wear down. There is no reason not to use #3 cable which is stronger and much more durable. The good news is that if you have a friend with a swager, you can replace the #2 cable with #3 or even #4 (I did this with all of mine). Another dislike is that they are hard to clean in corners. You are seeing more and more of these fixed (especially the bigger sizes) on Yosemite big walls. Even if you can clean them, it can be quite damaging to the rock. The Moses Tomahawk solves this issue by twisting the bottom of the piton.
The smaller sizes are great for nailing on tiny cracks on Yosemite big walls. The medium and large sizes are often even more useful as they can replace the need for a Lost Arrow or Knifeblade. The bigger sizes are good for clean climbing and sandstone big wall climbs. Both are generally for routes that are A3/C3 or harder. You don't need these for most of the popular trade routes.
At $18, these are little expensive, especially in the smaller sizes. The Moses Tomahawk is only $13.