Very accurate in its appearance. I can't really fault it beyond the tops of the funnels and the scale; the chimneys are white all the way to the top, they just appear blackened in photos perhaps (I don't know exactly) because of marks from the smoke they used to let off. So The size; I just looked it up, is 108m height.

An excerpt from wikipedia: "The building's gross dimensions measure 160 metres (520 ft) by 170 metres (560 ft), with the roof of the boiler house standing at over 50 metres (160 ft). Each of the four chimneys is made from concrete and stands 103 metres (338 ft) tall with a base diameter of 28 ft tapering to 22 ft at the top." It looks slightly smaller than that. If you did want to make it bigger I imagine it would be easiest to use MCEdit to clone it to 1.5 size or whatever is needed, rather than rebuild it. I don't think it's all that bad anyway, not saying it needs a redesign or anything. Far from. Just giving feedback like you asked. I think it's  very good :D

Oh btw these cranes might interest you too. They're located on the little pier outside Battersea power station on the thames. I think they were for heaving coal out of barges moored to the pier. They're defunct now like the power stations but still there, and pretty tall as you can see.