I would advise against taking notes in class on a computer etc. You won't keep up if you have to take down equations and structures. You need a pen and some paper.
So what you want is an entertainment machine with a word processor. Get a netbook/laptop. Specs are higher than tablets, they're cheaper, and you can install all the software you need. iPads, and I suspect most tablets, are toys - you can't do real work on them because you cannot install software like chem office, mestrec etc. (as far as I know).
I can't really suggest a model because I've had my netbook (Samsung NC10) for ~2 years so it's pretty much obselete - that said I still use it at work every day for writing documents, processing NMR data, chemdraw, email and surfing. At home I watch movies (external DVD drive) and stream video on it. It has everything I need.