I like that it has some of my favorite features (quick access, ability to attach files) at an affordable price point.
It hasn't been updated in years so there are quite a few bugs with it nowdays - but we're still using it as our only chat app for internal communications! There's nothing specific about nimbella commander that makes me dislike anything; it just seems outdated and not worth paying money for when other options exist free or almost-free. We use slack internally - which includes all employees working remotely from home. This is helpful because everyone can communicate easily through this tool.