There's an intersection on my commute that has one of these and I think it's awful, mostly because of the placement. It's about three-quarters of a car length back from where cars stop at the intersection (Google Street View for the curious: https://goo.gl/maps/hYbfF8qdCkD2). Probably 75 percent of the cars that use the right lane at this intersection are turning right. Because of the way the curb is constructed for the right turn, a bicyclist has to effectively leave the traffic lane to push the button, and if a car arrives while you're doing it you're stuck in that no-man's-land between the curb and the traffic lane. It feels unsafe to me. If I get to the intersection with no cars ahead of me, I try to approach the button at an extreme angle so that my rear wheel sticks out into the traffic lane, but that usually doesn't stop cars from going around me and then hugging the curb for their right turn.

The worst part is that this particular light is triggered by camera rather than induction loop and it doesn't pick up bicycles very well, but if I complain to the county they tell me I should push the button. If the button weren't there I could probably get them to adjust the sensitivity of the camera.