That is good advice.
While wuqi's advice is sound, but its a chicken and egg situation. When buying from developer, it is usually "off the plan" and construction has not yet started. By the time the building is mostly constructed, most of the units would have been sold. You wont even get a chance to buy at that time.
So imho, buy from developer when buying new/under con/off the plan, the advantage is that you get discounts/rebates, choice of units to choose from. Disadvantage is that you cannot view the completed unit.
The only way to get completed unit is to buy resale or if you lucky ...leftover units from developer...and leftover units are those which everyone else dont want...e.g. close to TNB station la, at T-junction la...number 4 lah etc.