heh. i loved the PS2 controller and think the PS3's sixaxis isn't too shabby. during the previous generation, plenty of people remarked about how natural the PS2 controller felt and how awkward the Xbox controller was. back then, we were mostly playing Metal Gear Solid and JRPGs. while the 360 has introduced vast improvements to Microsoft's design, the sixaxis represents a much more tried-and-tested design and seems to be more versatile for classic fighting, platforming, menu-driven, and puzzle game designs. it gains most of it's versatility from the fact that its design is D-pad dominant. the D-pad allows for discrete, canonical, directional inputs (up, down, etc.). its analog inputs are fine as long as you don't have to be too precise.
The 360 controller is analog stick dominant and seems to be optimized for FPSs and over-the-shoulder perspective games, where movement and camera control are integral to gameplay. i never played a lot of FPSs on the PS2 (insufficient analog control) and i never played a ton of fighters on the Xbox (insufficient D-pad control). Of course, for me the solution was to get better at using the analog stick for fighters, but I still have trouble with ->-> tap inputs (forward-forward to engage a dash attack in Soul Calibur). I also still whiff quite a few dragon punches in Street Fighter II. Overall, I think the 360 pad is a step forward for gaming. Console FPSs are more popular than ever and the superior analog sticks/trigger-like shoulder buttons are very accommodating for that style. but it is still not perfectly suited for all games.
when it comes to D-pads versus analog sticks, the trade off is that while the analog stick is more spatially precise, the D-pad is more temporally precise. spatial precision helps aiming while temporal precision is more likely to benefit fighters.
I'd also say that in general, I prefer the PlayStation's face button (X,O,triangle,square) sensitivity over that of the 360's face buttons (A,B,X,Y). they seem to be built to better handle rapid button tapping. no one has mentioned this yet.