There are risks in any real estate transaction, but buying new construction has several unique ones:
1) Contract Risk - builders use their own contract and rarely (if ever) allow changes. Obviously the contract is written in the builder's favor, but how will you know which terms are commonplace in the local market and which are uniquely theirs?
2) Financing Risk - If the building isn't ready to be delivered yet, the buyer assumes any financing risk between contract date and delivery. If interest rates double between now and then, for example, it's the buyer's problem. Similarly, any change in the buyer's status (e.g., job loss) is rarely accepted as a reason to get out of the contract. Best case is that you lose your deposit and walk away.
3) Delivery Risk - Again, with buildings that aren't complete, builders write in a clause that give them a specific time frame-often 2 years in this area-in which they can deliver late with NO consequences. If a buyer's lease is up or they have no place to go, that's the buyer's issue. It also adds to the Financing Risk (see #2)
4) Sales Risk Part A - If the builder doesn't sell out, then it's nearly impossible for a resale owner to price competitively. Consider the math--a buyer purchases, and has to mark it up to cover their own sales costs. How will a resale ever compete with a builder that doesn't have that markup?
5) Sales Risk Part B - If a builder doesn't sell out, and money is getting short, they may decide to "repartment" the building - that is, convert partially to apartments. That's a bad situation for owners (who now have tenants in their building) as well as for re-sellers (who would buy in a building when they can rent for much less in the very same building?)
6) Fees - Not really a risk so much as an FYI. Don't get too excited about that huge closing cost credit with use of "preferred lender and settlement attorney." They're "preferred" because the fees are higher in the first place. Know what a reasonable fee is so you can make an informed decision.