Well, there is a forum in Spain where lots of people have tried it and reported on it and shown pictures.
The consensus is this:
a)it's cheaply made "by hand" but works surprisingly well.
b)Because of this, it's considered grossly overpriced (a piece of molted plastic with a wire badly inserted and a socket)
c)About 50% of users say installation is not as "trouble free as claimed" (this is expected from all "solder-free" solutions ... they are finicky with placement, preassure, etc). They say it takes a long time to "get it right" and that a multimeter probe to check the contacts is very recommended.
d)About 10% of users are very dissatisfied, but some 70% feel ok and think it's worth it for them.
e)Many report intermitent problems after successful instalation, but still think they are rare enough to be worth it.
f)Everybody agrees: support, service, etc from the store that carries them exclusively so far is HORRIBLE, with ample delays, claims of stock when there is none, sending wrong versions or whatever. They do, nonetheless, try to answer emails and try to apologise, but plenty of broken-promises. They don't accept returns.
In short: this is a cheap, home-made product that can not keep up with the demand and therefore has a hard time fullfilling orders and giving proper service. It's grossly overpriced. But seems to work better than expected given the low production values and, although a bit finicky, could serve some users that can not/do not want to solder anything on the Wii's controller. It's not "the best of the best" but it's also not a non-working-piece of junk (except for the usual 10% of customers which it didn't work for). So I'd say it's a little below what one would expect from it, definetly overpriced, but could serve its purpose to those in need.
Somebody should definelty make a proper "clone" of this thing.