Its quite the opposite for me. I've had the 13" macbook pro for a month and thought it was too small and I really hated the glossy screen so I moved up to a 15" macbook pro WHICH I thought was perfect but then I was within 30 days when the macbook pro lineup got updated to the i5/i7 so i got an exchange without the restocking fee and decided to pay a little more for the 17" i7 model.
At first it was huge compared to the 13" and the 15" but after a week of use the 17" actually looked normal in size! Everyone comments on how BIG my 17" is on campus but to me it looks and feels so small (I guess I got used to the size). And now I am very glad that I have the 17" with the express card slot (use usb 3.0 later on) and I love the bigger display that you get with the 17" as well as the very excellent and LOUD speakers! It feels like carrying around a slim portable desktop computer around with you.
The reason it doesn't feel to big is because it might have a lot of diagonal, but it isn't that heavy (many 17" desktop replacements are 10lbs+) and is relatively thin plus it has decent speakers