I've used micropore tape, available from any chemist. It sticks well, so id say it works well, but there is, of course, a limit to how much it can do, so i can understand how the differing reviews might arise. I used it instead of a bra, with some success.
Wouldn't recommend it except for very exceptional circumstance ( fell in love with a stretchy dress with covered shoulders, noticed only after i bought it quite how low down the lace panel which was inset right down the back went.
There is probably another kind of tape, double sided, which you can use to stick to dress and skin. The tape wont hold weight, but can, with some fabrics, stop it falling open to create a gap.
Don't expect there is much difference between brands, would be worth buying twice as much as you think you need and trying a few dress rehearsals.
Hope it goes well, nothing so likely as to kill the please of an event as not feeling secure in your outfit.