I lived there for two years, 1988-90 and it was wildly overrated as a holiday destination at that time unless you were a bird watcher.
I'm sure it's much better these days since there's been lots of investment, but Guatemala is 100 times more interesting (I lived there for two years before Costa Rica), and probably cheaper too. Mayan culture (current and from 1,000 year ago), the Spanish colonial period, and a capital city of 2 million compared to 200,000 in San Jose. But beach tourism is not really developed there, so if a beach is a must, Costa Rica is a better choice, otherwise, Guatemala has everything Costa Rica has, but way better.