I place my 5.3" phone in my pocket every day (Samsung Galaxy Note I), so the folks that think this is too big are typically iPhone owners with tiny 4.0 and 3.5" displays. Having used a 5.3" phone I will never regress and go back to anything smaller. The only decent images come at the widest angle, so it's OK for landscape photography but not people photography.
I've used 17" laptops for 9 years now, 6 years on PC and the last 3 on a MacBook Pro. I also own the new iPad (3rd generation). I can tell you that the Retina display on the iPad makes the images from my Canon 5D look stunning at full size.
My only complaint is that Apple has NO MacBook Pro 17" with Retina display. Photographers and web developers love the biggest screen available, and at my office I use the 17" plugged into two external 24" monitors, so for me bigger is always better.
I would never consider down-sizing to a 15" or 13" MacBook Pro.
News flash - most Professional photography equipment is purchased by amateurs just for the pure fun of photography. As a professional photographer I am often working at a wedding where Uncle Harry and Aunt Martha have more expensive gear than I do. The equipment is not what makes you a professional, it's the training, experience, business acumen, artistic eye, and the ability to stay in business. The best investment I ever made was to join an affiliate of the PPA and learn from others with more experience, attend workshops and seminars, etc.
This trend of allowing photographers to shoot without any thought and control of lighting and then "fixing" it afterwards is troubling to me. As a professional my goal is to control the light to make my subject look flattering and get it right in the camera the first time.