As an accounting major you are probably going to have to marry Excel. While Numbers is a great app, and probably makes the prettiest spreadsheets on the iPad, it's Excel compatibility is less impressive. While adequate for the occasional import/export of Excel documents, you are probably going to find you need to seamlessly work on the same documents on your iPad and desktop. That not only means good compatibility, but excellent cloud integration; like DropBox.
While still not perfect the other Office suite apps are better for this than Numbers. The most popular are QuickOffice, Documents to Go, and Office HD. I recommend you look into those. Each of them is pretty good, so I suggest you look closely at specific features that you may need.
BTW, I'm a Numbers user, and I love the app. I can't think of anything that would convince me to use one of the others apps; except needing better Excel compatibility. But I'm just a casual user of spreadsheets. When I build them it's for the entertainment, and to help others. (yes, I know that's a bit weird).