After 8 months of unbearable printing frustration with the HP C6180, the iP4500 feels like it's heaven-sent.
I bought the new printer on August 14th, 2008, and after printing some color photos, my verdict is: IT ROCKS!
Prints from the iP4500 are just plain terrific, and I don't even need to mess around with calibration or matching the screen to the printer to the paper.
As long as you're not looking for fine-art or black and white prints of gallery standards, any photo paper of reasonable quality will do, as the Pixma doesn't seem fussy about the type of paper it's fed.
Read more about my experience with the Canon iP4500.