I've used 5.5 for a couple of years. Started with the limited, free version, but found it so convenient to use (and so limited in that version) that I bought the full product. I wouldn't say that I've had any major problems (maintain a small home network with 4-5 computers in the ring), and once the initial setup was accomplished, it was really easy to add new computers. I will say that the "share" function is limited, but I don't really use it that much anyway.
does anyone use the linksys "network magic" program ? have you had any problems ?