I also have it in my Tacoma. At first I thought the same thing as you, it took me a while to get used to it because it is different that others on the market. To get used to it, I put a receiver in the hitch to guage the depth of the camera, and had it in there for a few months. I have removed it and now I am used to it, and it is pretty accurate and nice to have.
Good point -- the lack of depth and the "rounded" picture is the issue to me. I still use it to make sure there is nobody right there when I start backing, but from then on it is turned head etc that does the job