I got contacted by Research Features twice. Yes it's true they want you to pay for using your research. If that's enough to call them "predatory", they are. However, this is not about just publishing your work. It's not an academic journal. This is about making more visible work that you have already published, something that you probably can't easily do yourself just sending to another journal. They do some service, i.e., rewriting with a broad audience in mind, advertising, etc. They are upfront about payments, and for the money they promise to do some proper work. They also asked me for a personal discussion. I have instead asked them to tell me in written form what they offer. They ask for between 1500 and 2000 GBP and have sent a detailed list of their services.
I have not taken up their offer, however I don't have an issue with it. If they indeed do what they promise to do (which I haven't checked), I have seen worse things to spend my money on. Offering a service of this kind and asking to be paid for it is legitimate in my view. Whether the service is good and will be worthwhile for you is another question of course.