The Izzo Alex Duetto is clearly the machine of the moment - just look at the number of recent reviews. If you are making a purchase based on features - and availability - you may well buy this machine... and you won't be making a mistake. I've upgraded from my well loved 11 year old Pasquini Livia 90, expecting a minor improvement; what I got is a quantum leap in coffee quality. Especially surprising is the improvement in steaming - the Pasquini was very powerful, but I always had trouble with microfoam. The Alex, with the supplied 4 hole .9mm tip, produces beautiful microfoam effortlessly. Perhaps the steam is drier - I don't know, but it works really well.
The mechanical design of the Duetto appears to be quite good - the parts are well laid-out and the materials are top notch. I especially like the fully stainless frame - which means that there won't be any insidious rust happening in the hot interior while the exterior gleams. The exterior shell is made of remarkably thick stainless, and the double-wall construction is an unusual bonus which keeps the exterior (and whatever is next to it) relatively cool. The group is, of course, a work of art and heavy... it's likely that local gravity is slightly skewed by the mass of this thing.
Aesthetically... well that's up to you. The curved sides are quite attractive, but the raw-metal upper edge of the housing seems a bit jarring to my eye, lending a somewhat unfinished appearance which is at odds with the mirror finish elegance of the rest of the machine.
But... all is not perfect in Alex's world. Perhaps because of the recent popularity of this machine, plus design changes and production increases, the quality control seems to be suffering. I didn't see any significant problems with the mechanical aspects of the machine, other than a mis-adjusted group lever valve, which caused the pump to come on sometimes even when the lever was set in the "off" position - an easy problem to fix. More concerning was the mis-formed outer shell. The outer shell is free-standing at the top, and the cup tray drops inside it. The cup tray is laser-cut to match the curved radius of the shell, but mine is a very poor match - so much so that the cup tray must be forced in place; the shell is too narrow on the center of the sides, with excessive (>1/8") gaps elsewhere. This may not bother everyone, but on a $2400 machine which is "on display" it seems a glaring defect to my eye. I understand that the shell is difficult to fabricate with perfect radius, but the design should be modified to add support the shell near the top (to maintain the proper shape) or the manufacturer should exercise more careful quality control in fabricating this part. NB - I run a metal fabrication company, so perhaps I'm a bit picky; I fully understand how difficult it is to fabricate a curved metal part accurately, but if you're going to incorporate such a feature in a machine, you should do it right.
Note that because of the need to remove the cup tray to fill the water tank, this machine should really be plumbed-in... which leads me to another minor nit-pick; the machine comes with a nice braided hose, and the excellent "Chris's" on-line manual notes correctly that the fittings are BSPP, and there is a supplied "John Guest" 3/8" fitting. However, that's the end of the documentation on plumbing in, and I had no idea what these were. A quick check at the local HW certainly showed that there are no BSPP -to- NPT adapters locally. Eventually, after researching the John Guest web site, I realized that the John Guest fitting is a British self-sealing quick connect which can be shoved directly onto a 3/8" OD tube - but a bit of explanation in the manual would have saved me about an hour of research, driving, etc.
Control locations are OK, but you can't set the PID when the group is hot without risking burning yourself on the group (a minor concern - as Chris's instructions suggest, you can and should set it immediately after turning on the machine, in order to avoid this danger.) The on-off switches are located on the right-rear - pretty hard to reach if you've got a grinder next to the machine - and nearly impossible to see.
This commentary may seem overly negative, and that may offend some who only want to see the good after plunking down $2400. The Alex Duetto is not without flaws, but is likely the best machine and the best value in a very high-end consumer espresso machine. Over the short period I've owned it it's shown absolute consistency in producing great espresso and milk steaming, and I expect it to be doing so for the next 10+ years.