Costa Rica is famous for its coffee, so sometimes the lack of good coffee in cafes and restaurants is surprising. Many Costa Ricans just drink Nescafe.
The national beer of Costa Rica is Imperial, which you'll see advertised all over Costa Rica. Other Costa Rica beer brands are Pilsen (a pilsner) and Bavaria. If you're looking for something stronger, guaro is a fiery sugar cane liquor, served as a shot or in a cocktail.
Like in all Central America countries, be wary of ice or water-based beverages -- make sure both are purified.