It's probably safe to say that TSOG (Hey, that's a name in and of itself) liked Millar's UXM. So did I.
Hey, I like Loeb. I like Mad's art, too... he's one of my favorites when it comes to drawing cartoony comic art. Therein lies the problem for some of us, though. When we think of The Ultimates, we're not thinking cartoony. I think Loeb's and Mad's styles will blend together wonderfully, but I don't think that their styles will blend with The Ultimates all too well. From the reports we've gotten, both want to carry make The Ultimates more like the 616 Avengers... which, for most of us, isn't what we want.
I like Loeb, but I'm of the same mindset as a few others in this thread. I'll give Ultimates 3 a try, but if the first one or two issues don't do it for me, I'm not going to waste my money on the title.
Loeb/Mad's Ultimates 3 could very well be fine, a swell title with no delays and good stories. But even with all the delays that have plagued Ultimates and Ultimates 2, Millar/Hitch is going to be a tough act to follow.