Opinions on Citadel Securities

I received an offer from Citadel Securities as well as a few other shops (e.g. Optiver/IMC/DRW/SIG). While I am able to find out a lot about these other shops, there's not much about info on Citadel Securities. Does anyone know what it's like to work there? I heard the turnover there is much lower than the hedge fund side. Anything helps, thanks!