Blue and yellow chevrons beneath the bridge structure in the U shape like the excelsior had, I'd prefer a slightly darker blue as opposed to the paler blue just to make it look a bit more warship looking, somewhere between the excelsior blue and royal blue would look better. I think that the larger part around the window, phaser and registry area should not be as big a section coloured in I'd still like to see the red lines either side of the registry area and by the time the phaser arrays have been mounted there will not be so much area to colour in, I think for this section maybe just a slightly darker grey than the rest of the hull, too much blue I think. The blue on the saucer edge is good very excelsior-esque. Perhaps a blue circle on the saucers underneath in a recessed par tof the saucer like the excelsior and then bring the red line circle in a bit more starting the front corner of the impulse section. Going back to the topside of the saucer, the shuttlebay emergency hatch definately should be a darker grey not blue.
I certainly prefer the blue impulse reactors rather than the copper look.
give me a hour or so and I will attempt to colour in and alter on photoshop to what I think would be a good paint job.
I love like the double fins on the impulse reactor housing they're a definate keeper, although could you bring the reactors and the fins forward a bit to make some more room for the phaser arrays which will be mounted behind them.
Shes starting to shape up now!