It's a nice start, but there's more you could be doing with the palette, which would give you more ammo for your AA. The forth purple from the right in your ramp is strangely desaturated, since the shadow purple and the pink midtone on each side of it are much more vibrant. As that purple is now, you could pretty much merge it with one of the greys to give you room for another colour. So you could add another tone between the second and third purples. Or whatever, point is you could have another colour, possibly. Also, the pinks largely are a waste, you could probably get another colour from one of those and diverge the remaining pinks to give more contrast and get more use out of them. Overall there's very little contrast to the palette in some places and large jumps in brightness in others. I find colours are most useful when they're friendly with their neighbours in a diverse neighbourhood. That terrible analogy is meant to mean: the ramp as a whole covers a wide range of tones, but its a smooth progression from dark to light.
So, it doesn't seem to me like this piece is really shaded? It just seems to be coloured. If you're just out to practice AA/dithering/hue shifting, well okay, but I feel you best gain an understanding of those things by integrating them into existing art practice. It just doesn't feel like there's any form, and AA/dithering/hue shifting to me are techniques for communicating form better. But whatever, I'm basically ranting...
