Some of the greens look quite similar. A lot of the browns are really saturated, especially with red, making them look like they would only work for clay. Large columns of some color groups have prohibited you from adding a greater variety of other useful colors.
This
I do like the colorset though. Add a little more variety in the greens. I can see greens that look almost exactly like the ones in the standard row, get rid of those and make a new variety. Also add more variety in browns
Other than that, pretty good set :)
Also: since you have such a large section of greens and browns, I'd suggest not putting those colors in the other rows and instead using the other rows for other useful colors (since you do seem to lack some other useful colors)