Need some information on job prospects at Palantir.

I read mixed reviews of Palantir on Glassdoor so not sure about the culture of the company. Unlike most of the popular Silicon Valley startups, Palantir is quite secretive and not much information in the press. Only positive articles lauding the problems they are solving but nothing on their products or services. I interviewed with them a few months ago but didn't make past the phone interview. Now I have another interview coming up. Can anybody working at this company comment on their long-term prospects including chances of IPO in next 1-2 years? They are already making over $1 Billion in revenue (per Glassdoor) and have raised Series K round followed by private equity investment so why are they not going public?