I love DoW, and I play as all the armies, but my particular favorite are the IG. I didn't like that they put the cap on the Kasrkins and Ogryns in DC. Something about those hellguns just ripping EVERYTHING to shreds is awesome.
As far as the Necrons, yeah. They're nice and spammy. I usually try to get a second monolith started ASAP (only 350 power), then just set it to crank out group after group of warriors, get your tomb spyders to hoover the dead ones, and send 'em right back out again. The fact that they don't NEED the strategic points is even better. I usually keep a group or two of scarabs constantly building generators, since that's the only resource you need. I just wish there was more variety.