I have been using this hammer hand pipe for over a month. I am very satisfied with its design and functionality. I ordered the white. It looks great and sits well on any flat surface. I love how colors contrast with the white glass. Your flower vs the white / the black-gray ashes vs the white / the amber glow of the hammer when you get a nice cherry going. As far as function, the hammers deep pocket catches ashes. This allows for a smoother smoke. It's noticeable for me, coming from a pipe that was pretty much a straight shot.
I find that I have to take a few extra small puffs to get a good cherry going. This is not necessarily a negative. This means it smokes like a pipe opposed to a simpler bowl.
After a couple of smokes the ashes on the hammer get very dark and the handle turns a dark yellow. The bowl usually remains dark and ashy. The piece cleans well with warm water, rubbing alcohol, salt, + shaking. I always recommend salt and liquid solution. It's quicker.
I always turn to Grav for their very clean and simple designs.
Enjoy the smoke!