Is it good for downloading things like Wii updates? Does it lag?
I had one for a while, before I got a wireless router. I've heard people complain about it before, but for me it was great. I had no problems with connecting my Wii to it and I could play my DS online anywhere in my house when the thing was plugged in. Heck, I even played my DS in my back yard one day.
Just get a wireless router. Probably find a cheap one that costs just as much as the USB dongle.