I purchased a 13" rMBP last week, and so far I am really enjoying it. I have this nagging feeling in the back of my head though that I should exchange it for a 15". I've always had a 13" or smaller laptop, which is why I went with the 13" to begin with, but I'm really starting to question whether I made the right choice. I upgraded to a 256GB SSD and the faster CPU, so I am essentially paying the same as it would have cost me to get the 15" retina and either a CPU upgrade or 16GB RAM. I won't really be using the computer for anything that will take advantage of the dedicated graphics, so the main reason for getting the 15" would be the added screen real estate and the faster quad core CPU. I'm a teacher and the laptop will be primarily my work computer, and will be moved back and forth between my classroom and home each day. I've always enjoyed the portability of 13" laptops, but honestly I don't know how big a difference those extra 2" would make in terms of moving it back and forth between two locations. My biggest question is this. If I will notice a performance increase in the thing I use my laptop for daily with the 15", then I think it would be worth me exchanging it. If not, I think I'd rather have the 13" even if it isn't as good a "value". I use the laptop for browsing the internet, using the MS Office and iWork suites, checking email, and other typical uses. No gaming, no video/photo editing. Would I even notice a difference with the 15"?