My husband and I have just returned from a trip to Costa Rica. We stayed one night in Puntarenas and opted for the Alamar Hotel. We did not have a reservation and this appeared to be the best hotel on the beachfront. It was better than we expected, at $90 (peak season) and we asked to see the room before we committed. We liked what we saw, spacious with a huge King bed, overlooking the pool, TV, A/C, WiFi and a nice clean bathroom. The reception staff were friendly, helpful and the young man that checked us in had perfect English. The pool was a little noisy, which is normal, and we could hear music coming from the reception area - there was also a pool table there, but by about 10pm it was quiet. The beach was ok, very festive at night, with markets and a fun-fair and live music playing.
As far as I could see one would only be in Puntaneras to take the ferry to Nicoia Peninsula - there would be no other reason to spend time in this little town.
We parked out on the street, there was a guard and we were told this would be perfectly safe. It was, thankfully. Breakfast the next morning was ok, fruit, scrambled eggs, toast and gallo pinto (beans and rice) fruit juices and coffee/tea etc. This was included in the cost of the room.