My PS3's wireless works well when I'm playing online for the most part, haven't had any major drops during gameplay, which is surprising considering my connection can suck really badly at times. With in-game XMB, it's much easier to sign back into PSN when I get logged out, which is great. The media network thing's connection drops all the time, but works fine whenever I use that.
Edit: The Wii's wifi is the worst of any of my wireless devices at keeping a connection going for very long, which makes updating it a fun experience.