1. The people. Indifferent, kiasu, kiasee, selfish, greedy, no compassion for the fellow man.
2. The government. Enough debate about the MIW in these forums already.
3. Weather.
4. Lower pay to living cost ratio than other developed countries.
5. Nowhere to go on weekends unless willing to hop over the causeway. Otherwise, it's shopping centres again.
6. Everything is fake - fake beaches, fake parks, housing, false sense of security, people are fake too.
7. Customer service is terrible. Little to no consumer rights.
8. Reservist. Very annoying when doing a major project at work and get interrupted to crawl in mud and do childish things in the jungle.
That's why I left. Never looked back!

The only good thing about keeping the Singapore citizenship is the NSS/ESS shares every couple of years.