I really enjoyed my stay!
I was traveling first half of July with my 6yo child and was interested in trekking and swimming. This campground proved to be the perfect basecamp for trekking in the Kamenjak (you can avoid the dusty car routes and just walk along the coast), with neat cliff/stone beaches within 10 mins walking. Of course there is a beach on the side of the campground, good for lazy days, but we preferred others also because of the various boats stationing in the bay.
The spot we chose (W094 - blue category) was conveniently located near the toilets, market/restaurant, electricity and freezer. The spot was not perfectly plain but that turned out to be an advantage when we got a couple rainshowers and the water flew out without damage. I was able to place a decent size tent (about 7m x 4m) without much trouble, and had good shade and plenty of trees for hammocks and air drying clothes. Restaurant is decent and has good prices, just avoid the icecreams :) also I found it weird that they didn't serve breakfast... but the market has fresh bakery so you can make do.
The services were clean (slightly less so in the last few days as we entered high season) and we could find food and supplies at the market - though small. Fruits and veggies are quite expensive but good. Avoid buying fruit at the stand near the reception - it's wildly expensive; better to walk up to the centre of Premantura.
I felt like it was safe to let my child walk around alone and he had a great time. I had read that the freezer was dirty and the ice packs would get stolen, but I kept mine there for two weeks and only noticed more mess over the weekends, as is normal.
The whole southern area of the campsite, though very characteristic and pretty (at least the spots facing the sea) is less serviced and I wouldn't recommend it with children.

A note on electricity: sockets are the "shuko" kind, not the traditional camping one which I only saw in one spot in the whole campsite - better to come prepared with cables because they are hard to find and expensive over here.

Great money value overall, but I'd suggest to avoid the high season!

We’ve visited Stupice camp at September. First impression-the place is huge. There’s plenty of things to do, from renting jetskis, paddleboards, bikes etc. to bbq-ing at the beach side, snorkelling or simply chilling in one of the local pubs/bars. The facilities are in good shape, clean and accessible. Also the town of Premantura is only like 20 minutes of walk away with many shops, caffes and restaurants.
The camp itself lies on peninsula that can be walked or cycled around in just couple of hours through many paths leading along the coast. I’d highly recommend doing that as you uncover a number of hidden little beaches and bays that are absolutely stunning!
Over all to wrap things up, the place is really worth visiting but think well when do you want to come as it can get really busy during the summer season.