Had mine over two years now. Love it.

I had ordered it, sight unseen, and neither the appliance store nor I could work out whether the simmer ring was included or had to be bought separately (the store had only sold their ranges up to that point). So I emailed Bertazzoni in Italy to enquire. A named individual responded the next day, stating that it was included, but that if I sent them my address, they would send me another 'just in case'. Free.
So, now I have two, which is perfect, because I'm often making a sauce on the inner part of the big ring, and cooking rice slowly on the simmer burner.

I was very impressed with their response. The appliance store said they'd had good experience with them.

So far no service issues: the propane company initially forgot to adjust the settings properly when connecting the gas line, and came back to re-adjust, when I told them the flame was too high.

It's a workhorse. I stir-fry often, and we cook on it every day. Easy to clean: just a wipe with a damp sponge, followed by a microfibre cloth. And I'm a messy cook.
I've not put the grids in the dishwasher, in case the rubber feet come off, but they were easy to clean in the sink.

Hope this helps, but if you have other questions, I'd be happy to try and respond.

Thanks, I was really worried about customer service. Also, most new kitchens I've seen have GE or Wolf cooktops. I'm glad to hear about the cleanup being easy. I have three teenage daughters who love to cook, which is great, but they forget that cleanup is a part of cooking! I end up with baked on food all over. Right now I have a black glass cooktop that I find impossible to clean. The other questions I had were about the knobs - they look so different than most other cooktops, are they easy to operate? Are the burners sealed or open, not sure I know the difference anyway. Again, thanks for your help.

Burners are sealed which I like because it's much easier to clean. I have no difficulty with the knobs, but I'm used to the thermocouple system from European gas stoves. It becomes instinctive anyway - press, turn and hold down until ignition happens. If for some reason it doesn't, repeat. They're nice to grip, and smooth to adjust. I'm afraid I don't understand those people who complain about waiting three seconds for ignition: what's the big hurry?
On the other hand, I just spent a vacation in a rental cottage in England, with an induction stove. The touch-sensitive controls drove us completely crazy. Hated them. Different horses for different courses I suppose!