I borrowed my friends iPad for a month and the conclusion I came to was it is NOT good for school use YET. Here are a few tips and comments from my experiences.
1) Get dropbox. You create a folder on your computer desktop, load the program on the iPad, and then everything in that folder is synced to the cloud and automatically updated onto both devices. This gives your iPad a 'file system'. I believe you have to be online to access these files, since they are connected to the cloud, so if you are on the bus you're out of luck (come on iOS get a file system already!!!).
2) NotetakerHD is the best note taking add. It's a bit cumbersome and messy to write in, and for taking SHORT notes I think it would be great (for full lectures not so good). As a grad student myself it would be great for group meetings, visiting lectures, conferences, etc... where you just take a few short notes here and there.
3) Good reader is quite good for loading PDF files, organizing them, reading them, highlighting and annotating them, etc... I think it would be quite a good alternative to the massive stacks of scientific papers I have sitting on my desk. If only the iPad had a retina display, i could easily use it as my full time reader (PDFs are very readable, but full screen they are a bit blurry due to the low resolution of the iPad's screen). Personally i'm going to wait for the iPad 3 with a retina display and hopefully a file system with iOS 5.
4) I tried pages and keynote, as well as docs to go, and both of them were totally useless. If you are like anyone else in the world, you use ms word and powerpoint. The idea of being able to put my doc/ppt files into dropbox, and then edit/proof read them on the go was VERY enticing, but alas it doesn't work so well. I found that every doc and ppt file I loaded in BOTH programs was un-usable. The formatting was lost, pictures were lost, etc... Totally useless. Unless you natively create all of your presentations/word documents in pages/keynote on your mac, this will NOT work for you.
5) No flash is kind of a big deal. A lot of education websites like blackboard, etc... needs flash. My friend who knows nothing about computers tried my other friends iPad, and his only comment was "I wanted to watch a sports game but it doesn't have flash so i couldn't, it sucks". Also one of my collaborators is doing her MBA and they need flash for their online course work. It's a really common format that a lot of people need, and even simple things like filling out online forms cannot currently be done with the iPad. I know apple is very stubborn on this issue and will never get flash, which makes it a bigger reason not to get an iPad.