See www.linuxtr.net for the latest greatest set of bugs. Generally speaking the biggest problem that I've seen (with ibmtr) is that if you pull your connection from the wall the 2.0.x series of kernels would generally not recover.
This has been fixed in the latest version of ibmtr and the driver should now recognize when the link cable has been detached.
There are some laptops that don't want to work with the Olympic Cardbus adapter, for some reason the driver never sees the open interrupt from the card. I don't think this is a problem with the driver, but with the Cardbus subsystem, for some people this problem has simply gone away with a newer kernel and I personally have never seen it on the laptops I've used in the development of the driver (Sony Vaio Z505 and Dell Latitude CPx500).