ISD is very effective. After Operation Coldstore, the power of the anti-Singapore movement was decisively broken and PAP has been the dominant political force as far as sinkie can remember. Subsequent operations like Spectrum nipped other Marxist movement in the bud before they can grow into full-blown insurgencies. It's the same with the detention of Islamic deviants of JI and ISIS.
The American's famous CIA, on the other hand, had been exposed for their incompetence on numerous occasions. They allowed a civilian subcontractor called Snowden to download and smuggle out vast amounts of sensitive info, they failed to stop China's espionage on their home soil, and they totally got blindsided by the rise of ISIS despite being on the ground in the Middle East for over a decade.
Singapore's ISD is the best!
