Just came back from 9 days in Cuba.
We stay away from resort areas, so I have no idea how it works there.

In general, wifi access costs 2 CUC/hour on the scratch cards bought directly from ETECSA. Hotels of course same the cards for much more (I heard someone paid 10 CUC in their hotel lol)

These cards are good for all the hotels in Old Havana and in any public area.
No idea about hotels further afield, but I would suspect since Nauta is the only operator, its the same login procedure.

Havana, the queue at ETECSA on the main drag is long, but there are other offices. We bought our cards in Trinidad, only waited about 15 minutes. You can buy as many cards as you like. As with anything in Cuba, there are some entrepreneurs selling cards for 3 CUC to people in line if you dont feel like waiting.

Santa Clara: There supposedly was public access around the ETECSA office
Trinidad: The entire square around ETECSA is fully wifi'ed. Lots of people with laptops, phones
Cienfuegos: Wifi in Marti square
Vinales: Wifi was down, but again, the entire area around ETECSA is wifi'ed
Havana: Hotels in old Havana provide a nice air conditioned refuge (we used Santa Isabel in P.d.Armas). Just BYO card, and plop down in the lobby with your device. There are public wifi'ed areas as well, including some parts of Central Park.

Speed was very decent, certainly faster than some US airports for example. Skype is blocked, but whatsapp, facebook, etc, work just fine.

I expect this to change rapidly as more hotspots open up.