I managed to get it last week, and based on my experience would recommend visiting in person if possible (realise this is difficult if you don't live near a city that has one of their offices). I didn't have any problems with the online forms, managed to book an appointment for the next day, and I was able to make the couple of extra copies of some of my old visas while I was there. Had I done it by mail I guess I'd have had to send everything in again. It was done and ready to pick up - or you can choose to get them to mail it back - within 2 days. I can't really speak to whatever problems people are having with the website, but I would say once you get to the office they are helpful in making sure you have all the relevant pieces in order to process it.
I do know some people have had problems with fulfilling the proof of address requirement where students live on campus (not an issue if you also have a US permanent address, but tricky for international students). They do accept a letter from the University, this obviously just takes a bit of forward planning.