I had to buy a new printer as my old Canon i865 was not Vista compatible. My shortlist was the Canon Pixma iP4500 and this Canon Pixma iP100. Both featured excellent photo quality printing, and were comparable in print speeds. The only major differences were size (the iP100 being considerably smaller), and purchase/running cost (the iP100 being considerably more expensive on both).
I bought the iP100 because of its tiny desktop footprint, and have not been disappointed. The photo printing quality is just superb. Canon claims it is "photo lab" quality given its 1 picolitre droplet size, and I can only endorse this claim. It's no slow-coach either on photo printing. Trustedreviews.com recently reviewed the iP100 (and the iP4500) and found the print speeds pretty much identical on 4x6, 5x7, and A4 print sizes. So, "bigger" doesn't necessarily equate to "faster".
The only other thing to note is that the iP100 is actually what Canon describe as a portable printer. It weighs around 2kg and is easily carried around with just one-hand.
My one gripe ?? Canon still DON'T enclose a USB A-B cable in the box, so if you haven't got one already, you can't print from your PC/laptop straight away. When I spend 165 quid on a printer, I expect them to include a 2 quid cable as well, especially when this is essential to use the product - sort it out, Canon !