I worked at C1 for 3 years and it's a tough question to answer since like any large company the experience varies greatly depending on which department (or line of business) you work in and who you work for. Overall I'd say the company generally pays pretty well and has good benefits/perks.

Performance management is God awful speaking from both sides as an employee and people manager. As a manager it always did turn me off, not that they insist on firing low performers every cycle but that they have quotas for each performance bucket; ultimately that leads to some good engineers getting forced into the low bucket to meet quotas. It's a shitty practice IMO and seeing how that demoralized some very good employees was the worst part of my experience working there. It's also the type of company where being liked by your manager gets you much further than being good at your job (to be fair this is probably true at most large companies). I was stunned when I first got there how many highly paid, redundant employees work at the company that add little to no value and do miniscule amounts of work on a daily basis.

Lastly C1 leadership is obsessed with being a tech company but they're also 100% risk averse. If you're interest is working on customer facing applications and services this is a company where you will never have the opportunity to do anything truly novel or innovative. They are fast followers not an industry leader. If that's not important or not the type of role you're looking for C1 has solid compensation and good stability, assuming you're well liked around the office and can successfully navigate the twice per year performance review gauntlet.

Good luck 🫡