I've got large hands and the analog sticks are just too far down the controller compared to other consoles' controllers that have the left stick in the main position. Also I'm not too fond of the sticks' travel distance and they always felt a touch too imprecise for my tastes. The directional pad is great though.
I know that the basic design of these controllers hasn't changed in nearly 15 years! But I've always loved the design of the dual shock controllers. They're getting a little long in the tooth now, and I actually think the Xbox 360 controller is the first controller that I actually like more, since the DualShock has been released. When the "boomerang" concept was floated as a potential design for the PS3 controllers, I nearly cried.