I did my entire Tyranid army using spray paints and Quickshade, plus a few details by brush.
I used the paint on, paint off method for the Quickshade. In some cases I did a layer of Quickshade, let it dry, then did another layer to get heavier shading. I was using the lightest tone of shade.
I sprayed everything matte at the end.
I painted the army in effectively two long bank holiday weekends. There are four large Monstrous creatures, about 23 medium sized creatures and 66.6 Termagants.
http://www.dakkadakka.com/wiki/en/Hive_Fleet_Kielbasa