The new operating system for iOS devices, iOS 9, came out several weeks ago. It's always a good idea to wait a while before updating (remember, all updates are free) so that Apple can work out the bugs that often persist past the "beta testing" phase. At this point, several updates have been released to iOS 9, so I'd say you are safe to update. That said, you'll want to follow some steps to ensure your update goes without issue. Cult of Mac always provides a nice guide to these updates- please see this link for information on which devices will run iOS 9 and how to update.
I do a lot of observation and consultation as an SLP, and notetaking apps are essential in this process. I have often recommended Evernote for notetaking, and still do- it has some great features including cloud storage (so I just use student initials, creation of notebooks, and audio recording).
However, the simple Notes app that comes as part of the operating system received a nice upgrade with iOS 9, and I have been revisiting it in the last few weeks. Notes now allows you to:
-Create Folders to organize notes (like notebooks in Evernote)
-Insert photos in notes
-Create a sketch in a note
-Make a note into a checklist
Each of these features makes Notes a more interesting tool when working with or for students, and also simplifies recommendations around assistive technology, as students can now do more with the operating system itself as opposed to downloading a separate app that requires an account.
As an example, I recently observed a student I work with who is struggling in math class, particularly with the word problems presented at the beginning of each period. Having a peek at the process gave me a sense of the language level of the problems, and how the student approaches them. I noted the student went right to setting up an algorithm to do the calculation and had trouble understanding what the problem was asking. Using Notes I quickly typed out the problem and collaborated with a supporting teacher on a visual "story" of the problem and how sketches might be used to support the language and mathematical thinking both in our sessions and in class. Doing this in Notes gave me a sharable record of the visit, without having to deal with any paper (a bonus for me)!
To find out some of the other education-related features of iOS 9, check out Tony Vincent's great update on the new operating system.