Very interesting and useful view on the use and risks of using free online tools in schools. Main points are that how do we know that what students do and keep online will be retained? Need to have an option to get the stuff out of the tool and keep it in a safe place.
The comments also open the way to further investigate this - particularly from Karl Fisch.
Might as well use this tool than any other for editting photos. Don't have to worry about installing an application and it looks like it does everything you need.