I've learned that I need at least three different graphing or calculator apps on my ipads so my students can select the app most appropriate to the job they are doing.
Free graph calc is a free graphing app that has a calculator, graphing tab and a table. This one allows students to graph an equation and read numbers off a table so they can find important information. I find this one is good instead of say a TI hand calculator.
Desmos is nice for if a student just needs to graph and only needs to identify the vertex or zeros. This app allows them to touch a point and see the actual coordinate. My algebra 2 students are using Desmos to determine the zeros, vertex and axis of symmetry. So far they have not discovered a way to use a table on that one.
Finally, in my college prep math class, we just started working with logs and properties of logs. Even today many of the calculator apps will not process a log with any base other than 10 and you still need to utilize the change of base formula. I discovered that my script calculator will allow you to do a log with a base of 2 or 3 or any other base and get an answer without having to utilize the change of base formula. I am going to have my students check their work after they use the change of base formula to find an answer.