I have the 11" ultimate I got last year and I love it. It is my only computer so I rely on it for everything, though I do have an iPad 3 that I use as extension of my iPhone, and for books and signatures.
I have a henge dock with a 24" dell monitor, super drive, 500gb external hard drive, apple wireless keyboard and mouse and use it as a desktop replacement when I need more screen real estate. Thoug I really don't tax it too much, I mostly web surf, use Microsoft office, iMovie, and occasnally go into windows 7, it has never felt slow or underpowered. For just casually browsing the Internet I prefer it over my iPad because I know whatever site I go to will work on my MacBook Air, it has a larger screen for viewing movies, and can prop it self up. However if I have a lot of reading to do, I grab the iPad because of the retina screen is easier on my eyes.
I have a henge dock with a 24" dell monitor, super drive, 500gb external hard drive, apple wireless keyboard and mouse and use it as a desktop replacement when I need more screen real estate. Thoug I really don't tax it too much, I mostly web surf, use Microsoft office, iMovie, and occasnally go into windows 7, it has never felt slow or underpowered. For just casually browsing the Internet I prefer it over my iPad because I know whatever site I go to will work on my MacBook Air, it has a larger screen for viewing movies, and can prop it self up. However if I have a lot of reading to do, I grab the iPad because of the retina screen is easier on my eyes.