Started building my Flak-Maus last night. It may or may not be as just-not-right as I wanted it to be, but so be it. I've got the Dragon 72nd scale Maus, and it's quite a sweet little kit -- of course, this being the Maus, it has a million wheels, but they are cleverly engineered to go together smoothly. I put together most of the bogies in only around 25 minutes (I was pressed for time last night). And once that's done, you are virtually finished building the kit. The Maus was a big box, basically.
I've got two of the cheap little Fujimi 10,5cm AA guns that I'll rig somehow to put atop the Maus -- luckily they give you the dummy-weight turret, and I think I'll use that as a form of kugelblitz-type turret for the FlakMaus. Since they give you that in addition to the "normal" turret for the Maus, I'll probably build both up and display it mostly with the real turret, taking the flak turret out and putting it on the kit and cackling maniacally when I am all alone (scary thought, no?).
If this and the E-100 are any indication of the direction Dragon 72nd scale kits are going in, then I am very pleased -- these are both very handsome and very fun-to-build little kits. (Well, actually kind of big kits.)