The cost of living is high for some things, but low for others.
Alcohol is expensive, and eating in some of the restaurants (esp non-Asian food) is expensive. Our local Italian eatery (La Forketta) charges $22 SGD per pizza! Eating out at hawker centres is cheap and convenient, especially if you are a single guy who doesn't like to cook. You can eat a whole meal for $3.50-$6.00, plus add a drink to that or just bring your own. If you do your grocery shopping at FairPrice you can save more money than shopping at Cold Storage - a bit like the difference between shopping at the co-ops in Dubai vs. Spinneys.
It is much easier to enjoy nature year round here, unlike Dubai. There are lots of outdoor activities that you can do for free, like hiking at MacRitchie Reservoir, or cycling/rollerblading at the East Coast park. Singapore is so close to other great places to visit, like KL, Phuket, Bali etc, that you can plan inexpensive vacations to neighbouring countries if you feel that Singapore is getting too small for you.
I'm not single and haven't been out for any nightlife here yet, so can't tell you much about that scene or how easy it is to make friends or find a girlfriend etc.