We've got a lightspeed pop up tent and I think it's brilliant. DP isn't so convinced by it as I think he gets embarrassed.
We took it to the South of France as the beach where we were staying had no shelter or loungers or anything. I think it was brilliant. The kids had their milk in them, out of the sun, ate their lunch in it, and I was able to stay out of the sun too. DP burns very easily and even he sat in it. It was also handy for keeping our things in, out of the sun, esp the coolbag.
Where we stayed there were no beach shops nearby selling umbrellas etc so I'm really glad we took one.
We have also used it in cornwall and it was a good windbreak from the cooler breeze.
I got mine from ebay but costco also sell it. It has mesh windows on the 3 sides with covers that could be closed and these helped keep the shelter cool, but it would get hot if there was no breeze, but then you'd get hot in the sun and probably burnt too so I'd rather the tent.
The one we have doesn't have a uv coating but I would definitely try and get one with that next time. Also, there is a flap that can be closed for privacy so if you need to change or breastfeed its a good feature. Also when the sun is lower in teh sky so earlier in the day or later in the day, the tent creates a shadow that is also perfect for the kids to play in when out of the tent.
We also use sun suits and hats and suncream for the kids as you can never be too safe.