I've previously used two versions of the Herman Miller Aeron, with varying degrees of adjustments. They were a dream to sit in at first because of all the precise adjustments. The Aeron really lived up to the hype after years of use. It wasn't until I sat in a Chadwick that I realized the Aeron was too adjustable.
The Chadwick has less adjustments and less features to an Aeron, yet it's design is more intellent where it needs to be.
I always felt the highly adjustable armrests on an aeron were too much and in the wrong spot. I could never immediately tell whether both armrests were at the same height until I rolled up to the desks edge. The roundness of the rests were too round causing my forearms to hurt after hours of leaning on them.
The chadwick on the other hand has no lever or button to adjust the armrest. Pull the armrest up, with each level it makes a distinct click. To lower it, you have to pull it up to the max and "release" it in order to allow it to rereat all the way back down. You can only go one way and the levels are very noticeable. It's a loop with speed bumps.
The armrests pads are better too. They are sturdy subtle ellipsises with a semi-hard foam. Enough flex to lean onto, but supportive enough not to notice much cushion. They're almost flat and fairly wide.
The height adjustment is similar to any other work chair, so nothing spectacular. Although, the lever is well-designed because of it's position, almost directly next to the armrest, slightly toward the front, beneath the seat. If you needed to lift it up, it's easier to grab and raise by leaning forward. If it were more toward the front than the side it would be that much more awkward to adjust.
The tilt locking mechanism is opposite the height adjustment. The delightful thing about it is the shape and ease of use compared to other chairs which combine this function with the height. The rod is sturdy and its function apparent by its shape.
My favorite part about the Chadwick is the way it adjust when you lean forward. The Aeron does a similar action by moving the seat and back independently, but the Chadwick props you up, as seen in their product photo.
When I bought the Chadwick it wasn't because it was $100 cheaper than the Aeron, but that was nice. Months ago I saw Jon Gruber recommend by linking to Brett Terpstra who also enjoyed it. I've had mine for a few months now and so far I like it better than any chair I've sat in.