Real review from Boston guy here. My main interest was staying somewhere in Jaco for a couple of nights that had an ocean view close to the beach. Copacabana fit the bill, and the price was right. We were in room on 3rd floor, with Jacuzzi on balcony (we used quite a bit).
I really liked the staff there, everyone was very helpful. I'm an annoying person when making travel arrangements - Katia was awesome! And Raquel and I think Daniel (or David?) at the front desk were great too. John the owner also stopped by to talk with us. Nice guy. He recently lost his son, so feel free to offer your condolences.
I read some other reviews - complaints about problems with all inclusive, or that there is a coffee maker in room and no one ever brought coffee....and so on. Come on. If you read about the all inclusive you see you're not getting top shelf alcohol or beer/wine, you don't get everything off the menu. And when I asked for coffee, they gave me a whole bag to take to my room.
Room is kinda small...but it didn't matter to us. So it was all good for the both of us.
Oh, the beach itself is not-so-good for anything other than surfing. If you are looking for a nice beach to sit out, head for Manuel Antonio's public beach.
We had lunch at Poseidon's which we really liked. Tried dinner there too - but didn't work out as well (uncooked chicken, overcharge on bill).