@ Garcian Smith
To see what I mean, try an experiment: Hold either the 360 controller or a SIXAXIS/Dual Shock 3 with your thumbs in the air. Now let your thumbs fall naturally. Chances are, on the 360 controller, they should fall on the left analog stick (left) and the four face buttons (right). On the SIXAXIS/DS3, they'll fall on the D-pad and face buttons. In other words, on the DS3, the D-pad is where the left analog stick should be, and vice versa.
I don't agree, place your thumbs on the analog sticks and from there try to hit the different thumb controlled buttons. You can easily hit all the buttons without thinking, at least to me it feels much more natural on the PS controller.
Take a game like Ape Escape, imagine rowing a boat with the PS3 controller and the 360 controller using both sticks. That wouldn't feel right at all on the 360 controller. I don't think it's a good default layout at all. At least the controller is a little less bulky as the original XBox controller, else I wouldn't even have considered buying the console at all.
As with regard to weight, I like how light the Sixaxis feels. Hopefully the DS3 will result into cheaply priced Sixaxis controllers. Rumble means very little to me, it's cool for gunning (following the beat of the gun) but IMO it's often overused for things it's just distracting or feeling unnatural (Sony and Microsoft, why no simple on and off switch on the controller?), like vibrating when dying or hitting something. Would be nice if future games would sport extensive rumble options, being able to customize what to use rumble for and what not.