Had one bought for me recently, along with the pint cans. I’m very impressed, just look at how the head sticks to the glass. Apparently you can use it with other canned beers as well.
I bought one, and didn't really see the difference between it and a can of draught. Other than the Nitrosurge cans being £2.50 more expensive for a pack of 4. Not tried it on anything else though, as I'd assume you'd only use it on something reasonably flat?
I’m going to do a comparison, because all beer with a widget is normally well conditioned as you rightly say. I think this is better though, great head on it and super smooth. If I bought this in a pub I’d be happy.