Stayed here the first week of july and liked it a lot. The rooms are maybe a bit small and the beds are as hard as in any italian three-star hotel, but that almost goes without saying. Shower on the really small side, but other than that the bathroom was nice and clean.
Flat screen television and air condition in room. Also we found out that you could borrow an internet cable to hook up your laptop (free of charge), which was very appreciated since Sperlonga didn't seem to have any internet cafés.
Balcony with sea view absolutely worth the extra money. Very nice reception staff. Breakfast a bit boring, but quite alright. Sunbeds and unbrella on the beach included and the water was wonderful. Probably the best Italian beach I've been to (that includes Amalfi, Positano, Tropea, Alghero).
Sperlonga was just perfect size-wise. And in the beginning of july the beach was not overcrowded other than on saturday and sunday.