I've been using the DCF911B for a while now, and overall it's a very solid tool if you understand what it's designed for. This is a compact, mid-range impact, not a high-torque monster, and it performs exactly like one.
The first thing I noticed is the size. It's small, lightweight, and easy to handle, which makes it great for tight spaces like engine bays or suspension work. It's also comfortable to use for extended periods, which is a big plus compared to heavier impacts.
In terms of performance, it delivers around 250 ft-lbs fastening and 400 ft-lbs breakaway torque, which is more than enough for me. I generally use it for lug nuts, general automotive work, and basic maintenance and assembly work.