I have it off. I find no real need for it as I keep my dock relatively large.
I have moved it to the left side of the screen, and have never looked back. Between the title bar and a readable dock on the measly 800 vertical pixels of my MB, it just doesn't work out for me. Windows have to be that much smaller, so taking advantage of all that horizontal space seemed a much better option, to me (at least until I get a big external monitor with some REAL screen real estate to play with)