This model was bought almost a decade ago and has been rattling around for nearly as long close to finished. It suffered from inexperience and a bad can of Citadel primer. As a result, the original paint job was super heavy, rough, and had these scale like blemishes from the primer. Basically, the primer clumped and left a powdery residue, and the GW store manager said that it was normal and just paint as I normally would over it. This was obviously not correct. Regardless, I painted up the model and I was never happy with it. Years later I tried to strip it and start over, but the primer was so thick it would not come off. I ended up using some fine grit sanding paper to smooth it out as best I could. Rather than give up entirely I decided to make the tank look ancient and battle worn. I also added some of the many, many (so, so many) Dark Angels icons and such that I got from a Ravenwing Battle force, that were not available when I first bought this tank. The remaining pebbling gave the tank a worn look, and I used the new Eldar Flesh dry brush medium to give it a dusty look to match the natural wear.
Thematically, my Dark Angels are fully engaged in the legion building the High Lords of Terra fear they are, and this command tank actually recalls their status as the first Legion Astartes openly. I might be adding a few more bits to it here and there. You can see that it is missing a sensor on one of the sponsons and a smoke grenade launcher on the front headlight flaring. I'll be replacing those or adding another icon and a headlight, at the least. I may add a sensor suite or a communications dish up top on the spare (unopenable hatch).
Certainly the next step is to add some weathering powder to the tracks and the lower portion of the tank, as well as adding a little more soot and weathering to the exhaust vents and hinges. I just bought my first Tamiya weathering kit and am looking forward to playing around with those.