Depending on the level, you may have significant issues trying to put in conventional foundations, and might have to go with a more expensive raft or even require a French drain to be constructed around the property.
Dealing with wastewater/ sewage will also be issues if you don't have access to the public utilities. If you're into gardening, your options may be limited to water loving plants.
Areas with a high water table are more liable to flooding, as during heavy rainfalls, it doesn't take long for the ground to reach saturation levels.