D.P.
I use Photoshop all the time. (At work and home.) There is a learning curve involved to be good with it, but like with most things, it can be used simply or in a higher tech way. If you already have it, I'd say go for it. It's expensive, though, if you're going to buy it and there's probably less expensive "photo editing" software available.
Is she proficient with Microsoft Office? Word, Excel and Powerpoint are broader-use programs that she will most likely need familiarity in an office setting, etc. At work (marketing/adv) we use photoshop for design applications.