Will I actually wear this again once the sun goes in? That's the question that matters more than the print or the colour. If the answer's no, you're better off with something that does double duty, because a holiday dress that only works at thirty degrees abroad is a dress you'll own for one week a year.
The difference between a good one and a dud is almost always in the fabric before anything else. Proper linen, or a linen mix with enough body to it, creases but recovers, and it moves with you rather than sticking to the backs of your knees after an hour in a deck chair. The cheap viscose versions look identical on the hanger and then cling to everything the moment you sweat, which on holiday is most of the time. Check the seams too, and the lining if there is one. A dress with a built in slip that sits properly rather than riding up under the skirt is worth the extra, because nothing ruins a good dress faster than having to yank the lining back down every time you stand up. Buttons and ties matter more here than on most dresses, since so many holiday styles use them to do the actual holding up, and if a button is hanging by one thread straight out of the packet, that's your answer before you've even tried it on.
Fit on the body is where these dresses either earn their place in the case or get left folded in a drawer. Anything with a fitted bodice needs to sit flat across the back without pulling when you reach for a glass, and a wrap style needs enough overlap that it survives a breeze, a car journey, and getting in and out of a pool without a safety pin. Smocked and tiered dresses are forgiving through the middle but can swamp anyone shorter, so look at where the fullest tier lands, not just the length. These dresses are brilliant for actual holidays, warm weekends, and any occasion where you want to look dressed without trying, but they're the wrong choice for anywhere cold, anywhere formal, or anywhere you'll need to sit on a hard chair for three hours, because the thinner fabrics crease on sitting in a way that looks fine on a beach and dreadful at a wedding.
I packed the wrong one for years, the pretty cotton one that needed ironing before it could leave the suitcase, and learned to travel with the crumpled linen instead, which looked deliberate by day two.
When you next pick one up, check the lining sits properly and doesn't ride up before you check anything else.