I personally love it. Its no grape caulerpa. Its way easy to harvest out of any tank unless your tank is taller than about 24''. Don't be afraid to get your hands wet and move some sand and rocks around.
There are worries of it going sexual and it all dying but this rarely happens and mostly its just turned into aragonite. It doesn't chemically harm its neighbors but may release noxious stuff when pruned. If you really don't like it I would suggest tearing most of it out by its roots and getting a GFO filter. If you doubly really hate it try a biopellet reactor or by dosing vodka, vinegar or some carbon source. That will remove its source of nutrients and all the calcium in the ocean couldn't make it grow.
If you want to know more read on, if not its cool:
There are 5-6 kinds at least as species go. About half like sandbeds and have more extensive roots and the other like rock and have less rooting. As said by GTR it eats up your calcium cause its mainly composed of it. So it slows coral growth, especially sps. And adding enough CaCl to overcome your losses adds up especially in a large tank. Plus it can overgrow any coral cause it also uses nitrates, phosphates and other DIM & DOM mainly through its root system. It can also slow your overall flow in a tank if there is enough of it. It also traps larger particles of food or waste that you want to get to your skimmer.
Now the upside to Halimeda growth either in your main display or your refugium is just that fact that it consumes unwanted nutrients at a very productive rate. Again its no Caulerpa racemosa, but it will still help keep nitrates and phos down. But it is essential you learn how and when to prune or cut it back. Without harvesting it all the nutrients won't leave your tank. You can cut it instead of uprooting it. This will encourage a more robust or fuller mat of it by leaving the roots intact and may kill less of it.
It all depends on what type of tank you want to keep. I wouldn't suggest it in an overwhelmingly stony coral tank like on TOTM. But if you are just keeping clams and soft corals then some Halimeda may brighten up your tank! It just needs to be pruned to keep it from taking up too much light.
Wow! These links are from years ago, well maybe someone will read it...