Installation is quick and easy and shifting works as expected. Materials and build quality appear first rate. The pulleys spin well. I do notice a bit more chain noise from the metal pulleys which is mildly annoying but not a deal breaker. I do worry about how low the cage is to the ground and it may hit objects like curbs, but that's probably not really an real issue. The upper pulley wheel can contact the cassette when the chain is removed or de-tensioned. Not really a problem but noteworthy. Looks are subjective, I kinda like it and kinda don't. Can't tell if it's saving watts, maybe 1 or 2 is what I'm assuming. Bangs for the buck I see low, but if you have cash to burn, it's an option to consider.
The part itself looks great and a lot of craftsmanship went into it, but I am embarrassed that I paid this much for a drivetrain component. Too little gain for the price.