Griffin claims a 4x boost in speakerphone loudness and a max amplification of 25 dB. I did a before-and-after test in the quietest vehicle on hand in the Car Tech garage, the 2012 Toyota Plug-in Prius. Measurements were taken using a second phone running the Smart Tools app for Android's Sound Meter function. The bare iPhone 4S output a measured average of 56 dB. When we placed the phone in Griffin AirCurve, the measured loudness jumped to 68 dB. So the AirCurve doesn't exactly make its 25 dB loudness boost claim, but to my ear it's still substantially louder. Griffin's not just selling snake oil here -- the AirCurve really works.
The plastic arm's ball joint is simply pushed into the dock's socket after unboxing and gives a fairly good level of adjustment and rotation at that single point of articulation. Where most mounting arms for windshield mount kits have a suction cup of some sort, Griffin's AirCurve features a flat clip that's meant to work with either the dashboard mounting base or the very odd windshield cling base.
The dashboard base is simple; its underside is covered with a strong, permanent adhesive tape that can be pressed into the dashboard. The AirCurve's clip is then slid into the base. You'll have to leave the base in the vehicle when removing the AirCurve for storage, limiting its multivehicle use dramatically.