I can't say how good the Stanley is. We decided to go for the best we could get, a Honda Eu20Si 2000W inverter.
It's supposed to be the second quietest generator on the market (the quietest is the Honda Eu30 at 51dB, the Eu20 puts out 52dB). It could be heard for some distance at the muster (I had bought ice creams with me, and needed to guarantee they stayed cold - otherwise I'd not have bothered with the genny).
I've had absolutely NO problems with the Honda. It just runs and runs. 10 hours out of a tank of fuel (light load) and the thing has a nice steady hum, unlike the two-stroke things like GMCs etc.
That said, Stanley has a good name. They might have branded this generator rather than made it themselves, which only really means that they're happy to put their name to it.
If you can't afford the $2,000 price tag of the Honda, maybe the Stanley is a good buy. In the Honda's favour: you can link two of them together to get a constant 4KW (8KW surge) and they are extremely accurate in their supply of 240VAC. If the Stanley can couple up and it's fairly accurate, it might be a good buy.
Hope that gives you some things to look at to help you decide.