It's wonderful. When you hold a MacBook Air, you really get the sense of the impressive engineering that went into building the machine. When you invest in a Mac, IMHO, you really see that Apple's philosophy is partially based on cost versus value. The machines do cost more than PCs with more powerful configs, but they have greater value. You can actually have pride in owning one of these. And this is coming from a PC user who decided to switch only very recently.
The OS is great, and the whole computer feels like one unit. You'll find that everything is very intuitive in a Mac (things like scrolling, web browsing, etc.). That, I think, is part of the reason why it is not too difficult to make the switch. The battery life is really unprecedented - it lasts the full workday without a charge, and even more once you get home (12 hours on the 13-inch model, although many reviewers were reporting even 13 hours or so in some cases). The Haswell i5 (or i7) powers through almost everything you throw at it, effortlessly. Fans run quietly. Everything is where it needs to be.
I can't imagine what a MacBook Pro or iMac must be like (because of the student budget I have), but I hope to invest in one of those in the future too.