I bought a ballhead for my tripod back in the summer (Brand 'El Cheapo'). I use it with 35mm and some mf (Agfa Isolette). I bought it because I tend to cycle to most places and a ballhead is lighter and more compact for carriage. It is also a lot quicker to set up than my old pan and tilt head.
If you do buy a ballhead, be sure to also buy a two axis spirit level for the hotshoe/accessory shoe of your camera(s). Makes levelling a lot easier! I have used both ball and P&T for macro, I found the ballhead was better.
I don't think I will go back to pan and tilt. At least not for still photography. I still use pan and tilt for my video camera.
Not a comprehensive review, but I hope this helped.