I've had fantastic performance from my two Pietta guns over the last 4 years. But in my case I bought the slightly upscale blued/colour case version. And having seen a couple of the flat black "plain Jane" Milleniums I'd say that unless you're VERY tight for cash that the blued/colour case version is the way to go. The flat black Milleniums simply seem much to lifeless. You'll be looking at them a lot. It's nice if you find them pleasant to the eye. And obviously for me the flat black finish just doesn't do it. But as for shooting? Oh sure!
Note that these guns are also supplied with an overly tall front sight. Except possibly for black powder .45Colt loads you WILL have to shorten it to get the point of impact to match the point of aim. I had to file off darn near a 1/16 inch to get my two .357Mag versions to shoot to POA when shooting my .38Spl cowboy loads.
But hey! It's better than them being too SHORT!
Note too that depending on if you shoot two handed or one handed it makes a difference to the height of the sights. My guns are set for one handed "duelist" style shooting. And when I hold them with two hands they hit about 2 inches low at 15'ish yards. The hold makes THAT much of a difference.
Anyhow, great guns where it all counts. Just be prepared to tune up the front sight.