Since I'm still waiting for the arrival of my beloved Dewbacks, I'm whiling the time away by building a droid army (2x Cores, at this point).
Man are they a pain in the **** to build. I misassembled a few before I even figured out the front from the back of the torso, so I have ... er ... factory quality defects. The legs don't always line up flush -- I have a couple who look like they want to enter a limbo contest they are leaning back so far -- and lots and lots of fiddly parts. I finally just clipped everything out, created piles of droids, and went to work assembly line style.
Painting, on the other hand, has been a blast. The GW contrast paints have made short work of the droid army -- I've basically used three colors (two contrasts and a drybrush) and then they're ready for a few marking details and basing. For all the pain they took to build, they certainly painted up quick.
The droidekas had the same experience -- slow build (took green stuff to get the rollie bois on their bases) but quick paint. On to Grevious!