One of the reasons that the dreadnought hasn't progressed from there is that it's really just box modelling after that - draw cube, move points in space to give it shape, repeat until finished. Other than some tubing coming off the lascannons / flamer, it's a fairly tedious model to do from this point onwards
The fun part was the legs, as all the pistons are animated, so they work as they would on a real dreadnought etc. Or, at least, they should in theory. I've not tried to animate them yet.
ohmygodnoes animated zombie dreadnought legs chasing me halp!