Chantalle,
Besides the monthly instalment, you will also need to consider the running costs which can be quite substantial. This will include road tax, insurance (can be quite hefty now as they have recently increased premiums), parking (at own plc as well as when u go out), petrol, maintenance. Maintenance will be about once every 6 months, I estimate average cost will be about $150 per servicing. As for petrol, it pretty much depends on usage, my guess will be about $150 per month since it is an OPC?
The pros of course will be you can go practically everywhere! The cons is that the roads are really very crowded these days and getting parking can be quite a nightmare! Also, Singapore roads are not that user friendly so be prepared for rude drivers especially if you have not been driving for a while and a bit uncertain on the roads.