Sony Ericsson Vivaz is slightly smaller than the camera button
Three buttons are placed on the right side of the Vivaz. The volume rocker is placed closest to the top. It is a string-thin strip that feels a little sharp to me, but it has good travel and feedback. Interestingly, Sony Ericsson has bestowed the Vivaz with separate keys to launch the video recorder and the camera. The video camera button is in the middle, and is slightly smaller than the camera button. It is a single stage key, and works well.
The dedicated camera key is larger, protrudes more, and has better travel and feedback. It is a two-stage key for taking photos, and each stage is distinct, which will help users focus shots before taking them.
I've always disliked that dedicated camera keys can launch both the camera and video camera, depending on how long you press the button. It's been a problem for me on more than one occasion when I wanted the camera and the video camera launched, and vice versa. Using two distinct keys solves that problem nicely.
The power/lock button is a slight dash notched in the top edge of the Vivaz. It is barely discernible from the surface of the phone, and has minimal travel and feedback. Given the importance of the lock key on touch phones,I would have preferred something a little larger.