The WET54G managed to avoid the problems that the WET11 had when it first appeared, and properly bridges traffic for multiple computers not only in the same subnet, but also to other networks, including the Internet. The built-in support for Power Over Ethernet (POE) should make it popular with wireless experimenters and even some Mom and POP WISPs, too.
But it seems that for whatever reason Linksys chose to change horses on radios for the WET54G, they ended up with a poorer-performing alternative - at least for weaker-signal conditions. Let's just hope it's something silly like accidentally cranking down the Transmit power level, which can be fixed by a future firmware update.
If it were my money, I'd wait until Linksys issues an update adding 11g compliance, WPA support and, hopefully, a signal-boosting fix, too.