Pros
+ Lower prices because of some wear and tear (which varies greatly — check closely!)
+ You get the benefit of upgrades (finished basement, pool, etc.) at a depreciated price.
+ Established neighbourhood, current neighbours, etc., are known entities although they can change.

Cons
+ Home has been used by others.
+ No warranty for repairs required by law, although it can be made a condition of purchase.
+ If existing décor is not to your liking, it can be expensive and time consuming to change.