Be very cautious if you are thinking of buying a model. Having been involved with the construction of several model homes (when I was a construction super) and having inspected many others for buyers, I've seen numerous issues. Here are some reasons to be careful:
In many cases, the model is the first home built, using a particular plan. Anyone who's built homes knows that what the architect puts on paper isn't always possible in the field.
As the model is being built, PTB's (powers that be) decide to make some "adjustments" for many different reasons. Often these are made after the municipal inspectors have visited.
Some of these "adjustments" are done for aesthetic purposes, to make the model look more appealing. Not all of these changes will stand the rigors of daily life.
Bathrooms are purposesly made non-functional so visitors won't use them. This can cause issues down the road.
Windows are screwed shut, which can cause them to have issues with opening and closing down the road.
Some areas of the home, garages in particular, are used for different purposes. (ie- offices, design centers, cabinet showrooms) When these are converted back into their original use, alot of problems can be hidden behind the drywall. I've seen ducting blowing in the attic, live wires stuffed behind walls, to name a few.
As a particular model evolves, changes are made for the sense of logic. Outlets and switches are relocated for easier access, zoning of HVAC is changed, and piping is rerouted. The original model is more a "prototype" and almost never get the changes made.
Sometimes models are cannibalized by various tradespeople to get parts for houses that they are trying to get closed.
There are more things to look out for, but this is a good start. I'm not saying NOT to buy a model, I'm just saying that you really need to do your homework and not get caught up by all the bells and whistles that tend to make people forget that they are buying a HOME, not a MODEL of a home.