The color variation stays true to the game palett used in Starcraft 2, and to some extent Starcraft 1. Some areas such the smooth part on the head and tail should to some extent be a little bit smoother. The reason for that is because the overall feel of the model is quite noisy, and while the Hydralisk indeed is quite detailed, I believe some more variety with smooth "less detaily areas" would contrast a lot with the overall detailed model. While you have added some smooth areas, it still feels way too noisy. At least for me.
The colour on the "bony parts" should stop more immediate I think, right now the "arm/hands" feel airbrushed as it gradiates into other colours, and really doesn't match the great coloring on the body. Which is more direct, and less gradial.
Also the specular seems to be even, as it's shiny pretty much everywhere. I think some areas should have duller speculars as right now they feel glazed, and not rough. Maybe it's the lighting, but that's just the feel I get from it, from this particular picture.
Also, if you were to add a pedestal with related environment on it, a "foot" if you may, I think this model would look really darn good, and a strong piece for your portfolio. (If you're building one or whatever.)
Im a big fan of Starcraft, and I do modelling and sculpting too, but nowhere near your skill level. I think you've done a great job, and good luck in the future!
The model looks badass! However, the color texture looks extremely simple and not as detailed as the model. I'd rather see the model in grayscale than without a proper texture. Keep at it, this could be an awesome demo piece!