Here in the Toronto area, we have pretty good cable modem service. I have several friends on it, with generally good results. Also, you are dependent on the speed of the server at the other end. If the server you're connected to is, for example, an ISDN line, then you are downloading at 128K and not any faster.
Upload speeds are nowhere near as fast as downloads.
However, I was at a friend's house, and we upgraded his Outlook 97 to Outlook 98, downloading the 30 MB files in less than three minutes. When it works well, it is like having the whole world as your hard disk. Cable modems are far from perfect, but they are much closer to it than any competitor in sight right now.