Acorn has a more generous free trial which allows you to do everything you want with the application for as long as you want. However, a pink and green banner appears over your image after a while. This banner interferes with image editing a little bit, but doesn’t appear on the saved file.
Pixelmator lets you do a little bit, but when you save, it places a banner on your image, rendering it useless.
I haven’t bought either yet, because I haven’t been able to try Pixelmator out enough to see if it is what I want. Acorn is excellent, but there are a few UI issues that make me hesitant to spend $50 on it.
There are different cursors for different tasks. However, there is no intelligence in the program to guess which cursor you want, so if you want to move some text right after you placed it, you have to click twice to select the move cursor and then you can move it. I’d like to be able to click on the little handles around an object with any cursor to move it, but maybe that is just me.
Also the text tool seems to have a hard time figuring out if I want to select text or make a new text box. There is only one text tool and it seems to do both tasks, but I can’t figure out how to select text reliably.
From what I can tell Pixelmator has a better UI, but I’m not expert enough to just fiddle around to figure out if I like a program. I need to actually use it, and Pixelmator doesn’t let me do that.