Probably better build and more consistent quality then 90% of the commercial machines in 90% of the coffee shops. Really!
Positive Product Points
Obviously makes great espresso drinks. Perhaps less obvious is how easily and how consistently it does it. The temp at the head rarely varies by more then .4 degrees during repeated shots. Steaming milk is relatively easy and quick. It is highly customizable for your particular coffee and tastes and relatively easy to change at any given moment - which means your Black Cat is fantastic and then your next shot of Hair Bender is equally great. The GS3 is outrageously expensive and absolutely the perfect home dual boiler espresso machine. La Marzocco makes a fantastic product and we could not be happier with our purchase.
Negative Product Points
It's price and that you end up drinking a lot more great coffee so you lose a lot of sleep.
There are other reviews with lots of details. Simply, the design is very good looking, easy to use and well thought out. The inner workings provide for a very consistent temperature control and consistently beautiful shots. It really is a very very good design. It fits easily under counters with cups warming on top. Switched to a dry steam wand and get perfect micro form almost every time. Very fast. Easy to clean and service. Clear instructions. Unpacking and hooking up took maybe 45 minutes. Dialing in the "perfect" shot takes a life time - but a fantastic shot took about another hour (had to dial in a new K10 grinder as well!).
Called Chris's coffee where we had purchased our Vivaldi II 7 or 8 years ago (and we never had a single problem with that super quality espresso machine) and talked to Mary intending to buy another mid-priced dual boiler machine. After some great advice from her and a lot of reading on-line, we decided to purchase the GS3 at Chris's. Always great service, honest straight forward advice and help, and very fair pricing.