Textbooks on iPad

Hey guys,

I'm a college student and have seen a bunch on using a iPad as a main source for textbooks. I know there is an up and coming site/service, KNO, that has a lot of textbooks, but how effective are they really? Would I be able to have all of my textbooks on there and be able to take notes, bookmark pages, and effectively study? Does anyone have experience with another app or service?

Thanks!

Zac

PS. I need some good answers so I can convince the parents to buy it instead of me! ;)