Context: I have a slightly biased view as I use Photoshop, Capture One and Illustrator. I have also used tools (with varying degrees of overlap) like Snagit Editor, ACDsee and Affinity.
If I was advising a person to get an image editing tool I would look at what they needed it for and would rank the complexity of their needs against the tool with a complex and complicated set of tools like Photoshop / Capture One followed by Affinity then in the middle and close to it ACDSee and a super simple tool like Snagit right at the bottom before the free tools. Ask if they wanted to go byond the simple tasks an learn etc. I know there are open source tools that would also fit on this grid but I don't know them well.

Rabbit for me is above Snagit, not very close to ACDSee, but nowhere near Affinity (if you're used to PS go for this) and given how much Afinity costs, a bit of a hard sell for me. But Affinity has a steep learning curve like Photoshop. For example I wanted to import SVG and .AI files, and Rabbit doesn't support that (as far as I could tell).

However, if you want an easy-to-use tool then Rabbit is good, UX/UI is pretty good. Bonus: they have Windows and Mac versions, but for Windows it is based on (sitting on top of an) Adobe Air framework, so not exactly a native app. It was fluid and easy to use when I tried it.

If I was comparing Rabbit to Affinity I would give it 1 or 2 stars but for a person that only wants a simple tool to manipulate images, I'd give Rabbit 3 to 4 stars.
As you can tell from the tools I already have, I will likely not be keeping this but it was fun to try it out.