I currently have a 13" MBP on order and it should be shipping soon, but I have been thinking about canceling the order. I went to the local Apple Store today and say a 13" and 15" side-by-side and I must say I was more impressed with the 15" than the 13" but for only two reasons.
Screen Real-Estate
Any one knows that using a large screen for an extended period of time (I have a 24" on my PC) makes anything look tiny. What I didn't like was how much room the Dock cutoff from normal screen operations. Is it possible to resize the dock or relocate it to a different position so you can make Safari or iWorks even longer (larger) on your screen?
Brightness
Now I have read that there are some concerns with the 13" and their brightness levels depending the model screen you get. Can the lower brightness quality be fixed through calibration or are you stuck with what you get?
Seats
Why doesnt Apple but seats in their stores
Its hard to gain a true idea of which laptop fits you best when you tower over the merchandise 
Screen Real-Estate
Any one knows that using a large screen for an extended period of time (I have a 24" on my PC) makes anything look tiny. What I didn't like was how much room the Dock cutoff from normal screen operations. Is it possible to resize the dock or relocate it to a different position so you can make Safari or iWorks even longer (larger) on your screen?
Brightness
Now I have read that there are some concerns with the 13" and their brightness levels depending the model screen you get. Can the lower brightness quality be fixed through calibration or are you stuck with what you get?
Seats
Why doesnt Apple but seats in their stores