In answer to the question in the title, yes they do work, but in the body of the message you ask how well. I have a pair in my barn that I bought cheap on Ebay, so a quantum difference from your intended application. Mine don't work great, but good enough out in my barn. I have tried better ones, but honestly I think wireless speakers are a compromise. Since your intended purpose is for appearance only, my recommendation is to avoid them. If you really have to try them, try to get them locally from a place with a very liberal return policy. You very well may find that the higher end ones will work okay for you, but I think wired speakers are better, if you can go with wired speakers, do it.
I've seen a bunch of mixed reviews at Amazon.com over the past few months. I am kind of considering them too. Some of the higher priced wireless surround speakers ($500+) seem to perform better but not without complaint. The stated distances by manufactures were a big part of the issue.
What I'm planning to do is go and test them out at Best Buy first. I'm only looking to have about 15'-20' of distance between my receiver and speakers which shouldn't be asking for a lot.