Received my PR application rejection letter about 3.5 months after submitting all my documents.
Also got the kiss of death: No invitation to re-apply in XX years.
About me:
Race: Indian
Age: 30+
Field: Corporate [edited for fear of outing myself]
Current Salary: $30,000+ per month
Time in SG: Almost 6 years
Marital Status: Married to Singaporean citizen for almost 4 years
Kids: None yet, but one on the way

Educational qualification: Undergraduate and graduate degrees from top US school [edited for fear of outing myself]
Tax: Paid 4/5 years worth
Wife: Born in Singapore, naturalized Singapore citizen when young, but an Indian passport holder at birth
This was my first PR application. I think my application was fine except for my race and this complicating factor:
Have a drunk driving fine/arrest (no jail time) from the US 8 years ago that I declared and have declared on my past 3 successful EP applications (yes, I know, incredibly stupid, selfish and embarrassing, and still paying the price).
In all honesty, I thought I this application was still going to be successful. Very disappointed it didn't go through since we had all intentions (and still do for now) of making Singapore our permanent home for our new family. Despite popular wisdom, I'll probably re-apply once our baby is born and see what happens. One question to the group: Does a PR rejection affect your prospects of EP renewal?
Anyway, I hope this anecdotal information is/will be helpful to others in similar circumstances.