Public health in Costa Rica compares favorably with that of many developed countries. No shots are necessary to come to the country. Medical facilities are numerous and dependable. Unlike other Third World countries, it is safe to drink the water. Costa Rica, in general, is a safe place.
Most crime is the petty type.
Don't leave valuables or personal documents unattended or in a parked car. Buses are widely used and economical. Travel by air within the country is adequate and inexpensive. You may drive up to 3 months with a valid drivers license issued by your country. Theaters, movies, restaurants, bars and discotheques with live tropical music are abundant and lively even on week days.