Katie,
you can (and should) expect a very good performance from photoshop. among the freewares, you will have the burden of deciding which one will suit you.
meanwhile, when the best of the freewares are set together with Photoshop, you'll end up deciding according to the most important criteria - yourself. that is, what you can do by now, and how much are you willing to get better using a software.
for example, Pixia can draw almost anything you need to draw, depending on your level as an artist and your knowledge of it. having said that, you'll appreciate an excellect artist using Pixia (or any other freeware) more than a novice using photoshop.
you might want to check some artworks using Pixia, as done by a very good artist.
Click here.
as a recommendation, if you are able and willing to purchase photoshop, go ahead. if the cost is not worth the cause, try the most recommended freewares. you can see some at nonags.com.