Pros
You are entrusted with the sacred duty of keeping Singapore ahead, honestly, there is probably no other company like this. Unique opportunity. You have access to details that are secret and this can help you learn new things about the world. The job is very secure and there is no danger of pay stagnating. Promotion is guaranteed given enough years in service.
Cons
No. 1 gripe is that the management style is excessively deferential and hierarchical. Analysis is driven by what is most likely to get cleared. Analysts do not learn how to think and analyze issues systematically, but rather to present info in an anodyne airtight way. This is so the Ministers and internal management have nothing negative (not necessary anything positive) to say. Far from being a think tank with secret info, more like a monastery on a forgotten Tibetan hilltop. Not much chance to learn new things outside of civil service lens. Technology? Forget about it. Expertise is not valued unless you are a senior officer. You need to "prove your worth" first by going through the same path as your seniors. Internal postings are becoming less opaque, but often "who you know" rather than "what you know". In summary, if you have a vision or a desire to change things, you need to slowly spend decades here growing your empire and coterie of like-minded individuals. Unless you are lucky enough to be talent spotted by a senior officer and catapulted to the forefront. It used to be a relatively scholar-blind place. But new management values trying to recruit PSC scholars so they aggressively recruit scholars and give them more opportunities than the regular officers. Also is far more likely to hire mid-career officers such as SAF officers or other civil servants, and give them better pay and roles. If you want to join, join as a mid careerist.