I'll just post my input here and explain why I bought a MacBook Pro 13" recently for university, instead of opting for one of my other Windows options (Samsung Series 7, Lenovo Thinkpads, Toshiba Portege).
I've always been a Windows guy and this is my first Apple product too, so you should keep this in mind before you read ahead.
Note: I am going to be assuming that the MBP 13" is classified as an ultra-book for all intents and purposes due to the great battery life and light weight, even though it technically isn't classified as one by Apple.
1. Aluminium Unibody: Aesthetically pleasing, seems pretty solid, no noticeable air vents, fairly light. Most other laptops (even those in the same price range) make extensive use of plastic in the body and the build quality will generally be lower, not only because of the plastic, but because the body is assembled in parts and may result in creaking and bending. Toshiba Portege series laptops and Lenovo Thinkpad Carbon X1 is an exception.
2. Hardware / specs: Standard mobile processor instead of ULV one leading to better performance (Ask if you want an explanation). Most, if not all, other laptops with the same battery life (6+ hours) have ULV processors. User upgradability - I can upgrade to an SSD and add more RAM later on by myself instead of having to take it to Apple and pay a premium for the same upgrades.
3. Good connectivity: ethernet port, optical drive, thunderbolt port, firewire (all these things are usually not present in many PC "ultra-books").
4. Battery life: Following point 2...The battery life is comparable (and often better) than the ultra-books on the market, without compromising on performance with a ULV processor.
5. Software: Mac OSX - incredibly optmised for the hardware as OSX only has to deal with a fixed set of configurations of hardware and not provide guaranteed support for all configurations like Windows, Unix-based - so the memory management is better and free RAM is used in a more efficient manner, Secure - not because "derp I are c00l MaC don't GET ViruS lololol" but because Mac OSX's market share is too low for hackers and crackers to bother spending there resources on making viruses for it...not saying there are no viruses, but they are very few in comparison with Windows. Gestures - At first the cool gestures with swiping and multi-touch support feel like gimmicks but the more you use them, the more you like them and appreciate their usefulness in everyday computing. Xcode - so I can legally program apps for Mac OSX and iOS in Objective C.
6. Personal preference: I wanted to try something new and I hadn't ever used Mac OSX or an Apple product, so I decided to try it out. Basically, I wanted to see what all the fuss was about.
7. Durability: Or rather what I've heard of Apple MacBooks and how they are very reliable and last long. I want something that will last me the next 4 years and I didn't want to risk with anything of lower quality. (If I wanted to risk it, I would have definitely gone with the Sony S13, which is cheaper and packs a discrete GPU too. The only reason I didn't go with it is because I haven't had a great experience with Vaio's in the past and because of this:
http://www.sonyvaiosucks.com )
If I have missed anything, I will edit it in later. Feel free to comment on why you think I'm right or wrong, but please do make sure you can show me a comparable machine at a significantly lower price. Tip: The Toshiba Portege is the only line-up that comes close to the Apple MacBook line-up in terms of quality and performance...and you know what? They cost pretty much the same as the MacBooks. Keep in mind that I researched the laptop market for over a month before I bought this MBP last week.
Also, I have another Windows laptop (Toshiba Satellite L655) which I love, but I'm not taking to university due to low portability.