I just recently purchased this machine after having used a Rancilio Silvia for about 1 year. I settled on the Millenium after 2 months of research and have not regretted the purchase. The machine is a pleasure to use, although it is not completely fool-proof. Learning how to "properly" use the Silvia, i.e., temperature surfing, was a big help. It also rates very high on the "cool" factor with friends who don't know from espresso.
You've no doubt seen the pictures of this machine, so I won't discuss the visual appeal. And the size and weight are documented at Chris' Coffee. Keep in mind, this is a large machine if you are used to something like a Silvia. Plan accordingly.
During my research, I found a few owner's of Isomac Tea and Euro Junior machines that had done some very detailed research and provided extensive suggestions on using these machines. Since the Tea and the Junior are identical "under the hood" with the Millenium, this was very useful information. The primary issue of concern is that the water temperature exiting the group after the machine has been on for some time is quite high. This is normal, since all heat exchanger machines are designed to be used nearly continuously. Since this is not the type of use that it will see in a home-use setting, the concern is well-placed. And I found that I did need to drain a fair amount of water before pulling a shot to keep from getting burnt espresso.
Although the water reservoir is fairly large, having to drain several ounces of water befor a shot would require frequent filling. Consequently, I decided to fiddle with the pressurestat settings in order to get a more reasonable setting. And here is where things got interesting. As has been documented, the Tea is about $200 less than the Millenium, even though they are internally identical. The cost difference, by all accounts, is due to the rounded skin on the Millenium. I have no doubt that this is true after spending several hours trying to figure out how to get inside this machine! I won't go into details here, but it is quite an ingenioius design. Basically, the entire out skin, except for the back panel, is a single piece of steel. If you are interested, I took some pictures which I hope to have up on a web site soon. Keep an eye on alt.coffee for details.
After settling on a pressurestat setting that keeps the pressure between 1.1 and 1.2 bars, I think I've got the ideal setting for my purposes. After the machine has been idling, even for a few hours, I drain about 3 ounces of water from the group before pulling a shot. This gets the temperature to the point at which I can get a consistently good shot. And there is still plenty of steaming power for frothing at this setting.
The quality of the espresso is as good as I have ever had, anywhere, including the "holy city" itself. As for the steaming, if you can steam on a Silvia, you can steam on a Millenium. It just takes practice. Frankly, I don't do a lot of steaming, although I can make decent micro-foam. And since my wife isn't nearly the coffee-nut I am, she is very pleased if her latte tastes at least as good as what she gets at Starbucks.
I did, however, get a rise from her recently when I made an iced latte for myself. I set it on the counter after a couple of sips, and left to get something from another room. When I came back, she said, "your chocolate latte is really good." That brought a grin to my face. "There isn't any chocolate in it. It is just a regular latte." I never got that reaction with the Silvia. She was quite surprised, but this just shows how good the espresso can be from this machine.
Now I should also note that I'm roasting my own beans as well, so I've got as many variables under control as possible, short of upgrading to a full-blown commercial roaster. But that single comment pretty well proves that I must be doing something right.