Some teachers design questions so that someone with a ti-89 will have little advantage over someone with a 4 function calculator. I found that most of calc 2 could be done faster by hand, and perhaps just checked on the calculator.
Calculators can get really messy when dealing with trig functions. Because of all the trig identities and how they are all practically just restatements of eachother, you can represent a trig expression in a ton of ways. The calculator doesn't differentiate between them very well.