I just realized that you shared the UK link for glassdoor. Honestly, I can't speak for the UK office, they seemed fine. I worked out of their LA office, so maybe your millage may vary?
I don't work there anymore. I left that company for a literal 100% pay raise, their pay sucks that bad. I wouldn't really pay attention to the glassdoor, though the negative reviews are very close to my experience there. Lack of direction and poor management. Their technology honestly sucks. Its an insanely political place where if you don't toe the company line and say everything is peachy, they force you out. Like even pointing out serious weaknesses in applications or the absurdity of a project is seen as being a problem employee.
There aren't very many smart engineers working there honestly. One of the good things there is that they put junior engineers in charge of projects, which lets them grow faster than most places, but the problem is that they put a bunch of junior engineers in charge of projects so there is noone who really understands software engineering and could actually mentor others. Like if a senior engineering resume came to me from RV, I would treat it as a Junior engineer.
So fine place to start your career, terrible place to actually learn how to build good software.
RV is an incredibly shitty company. I doubt this company will last. The middle management there sucks and the company has no vision beyond "lets just do what other sites are doing." Their entire business model is about not giving a shit about the consumer and just ramming and hiding bullshit deals down their throats.
Talent wise, I have never worked with a group of assholes as delusional as the people who work there. Their technology sucks, and the people who are implementing are is extremely fucking dumb. They get distracted by shiny new technology all the time. This lead to all of their crap being this unmaintainable mess of crap powered by wordpress.
And if you tried to make things better, everyone there had the biggest egos you can imagine so any criticisms were seen as an attack on their character. One time there was this code that was super insecure with SQL injections all over the place and remote code execution vulnerabilities. When this was pointed out, the director who wrote that code 20 years ago tried to get someone fired. No quite a place I would trust for all of my personal information btw.
If you think you are the best, this place is for you. Shitty technology and shitty products that leave plenty of room to just coast with no real challenge. But if you are actually smart and want to work with real smart people, this place is not the place. One of the worst places I worked at in my career.