Roads are Costa Rica are not paved quite as nice as North America but any road through the major cities and highways are all paved. You will encounter unpaved roads if you go into the rural areas or small towns. As you venture off the beaten track, you will likely need a 4 X 4 in case you need to drive through a local creek or to dodge the potholes.
Many of the major highways are paved with some having recently been resurfaced. The roads linking the major towns and cities are also in good condition.
They are constantly improving on the roads. Every year the government commits to improving the number of paved roads throughout each province which is good for tourism and certainly improves the daily life of the local people.