Before you buy any outdoor set, check the frame material against your actual weather, not the weather you wish you had. A set rated for a covered porch in a dry climate will rust, warp, or fade within one season if it sits uncovered through real rain and real sun. That single mismatch causes most of the regret I hear about.
Where these sets go wrong is placement that ignores wind and drainage. A glass top table on an open deck in a windy spot is an accident waiting to happen, and resin wicker set directly on dirt or grass without any barrier will trap moisture underneath and start breaking down from the bottom up, long before the top looks tired. I made that mistake with a bistro set on a patch of grass that never quite drained right, and by August the legs had started to green and smell like a pond. Cushions left out through a full season of dew, even under a supposedly weatherproof cover, will mildew, and once that smell sets into foam, it does not come back out no matter how many times you hose it down. The difference between a set that survives and one that does not usually comes down to things you cannot see in a photo: whether the frame is powder coated aluminum or just painted steel that will bubble and flake within a year, whether the joints are welded or held together with plastic brackets that crack in the cold, whether the weave on a wicker piece is a real resin extrusion or a flat synthetic ribbon glued on that unravels at the first snag. Cheap sets also skip galvanized hardware, so the screws rust first and streak the finish before anything else fails. Pick a piece up at the store if you can and feel the weight at the joints, a flimsy connection usually gives itself away immediately.
There are real limits here too. A full set is the wrong move if your outdoor space is small or awkward, a narrow balcony or a tight side yard does better with separate pieces you can actually move around than a matched set that only fits one configuration. And if you are only outside a handful of weekends a year, spending big on an outdoor set makes less sense than putting that money into the deck or patio itself first.
The one mistake to avoid is buying the whole set before you have measured where it actually lives, full sun, full shade, exposed to wind, or tucked against the house, because the right material for one spot can quietly ruin itself in another.