I was looking for a coupler that looked better than the standard hook and loop but which also allowed for some operator interaction - mine is a small layout so the hand of god is a feature not a bug. The chain couplers really look the business. I particularly like that they are not "handed" - you don't have to worry about which pole is which when installing.
The downside, if you can call it that for a very off brand use, is that while they fit very nicely into NEM pockets, they do tend to drag on the track. This is a function of the NEM standards rather than the coupler design, and is much less of a problem if mounted at buffer beam height. This of course requires modification of rolling stock but I think it's worth the effort.
In a some cases, a few links may need to be cut out of the chain, this also helps shorten up the inter wagon distance when running. Very fiddly but again worth it visually for a small layout with only a few wagons.