I tried one also and found it only marginally useful. Here were the primary issues:

In the surf, the solid bottom prevented water from draining quickly, even with the mesh. This posed a possible danger and could result in the angler (me) being pulled down or off my balance by the weight of water that collected in the basket, even temporarily. In the surf, waves collapsed the sides and also caused the line to tangle in the bottom. Without putting something rigid in the bottom, the weight of heavier fly lines depressed the bottom and caused the line coils to settle towards the middle, causing more tangles and reducing casting distance. This could be addressed by inserting a somewhat rigid bottom with some sort of spikes attached.

Without some sort of spikes or fingers in the bottom, the basket only minimally reduced tangles. The thing seems to work best when secured to the leg. In a boat this meant I couldn't swing it around behind me and it was in the way when trying to move around the boat. Also the handle loop caught on things. There were other things I found aggravating but these were the most annoying.

When fishing from not surf environments from shore I found, leave, twigs and other debris caught in the mesh and was a nuisance.

I tried the thing a couple of dozen times in various environments and just didn't find it useful. The best thing I could say for it as it comes out of the package was that it packed down nicely. Putting a semi rigid piece of plastic with some pegs or spikes into the bottom does improve the utility of the basket.

I understand it works well for some people in their situations, it just didn't work well for me.